What would PS5 have sold this week if not for supply constraints? Direct comparisons to Wii U just don't make any sense until shipments/demand start leveling out. All of this is centered on the idea that PS5's current sales are reflective of demand and thus its in a Wii U dire situation.

Also the PS4 did not have any games to appeal to the Japanese market for a long time, arguably its first truly big title was not til FFXV which came almost 3 years after the system launched in Japan. PS5 will get off to a much better start having Resident Evil 8 and GT7 in the next handful of months and potentially FFXVI in the second half of the year. Although western games represent a niche market, the sales pull of titles like God of War/COD/Horizon etc are still respectable (100k+ opennings) and these western blockbusters are bigger in japan now and will be abundant on PS5 in a way they were not in the early life of PS4. 

Games already in development for PS5 will not just be able to Switch to Switch , equally their appeal in the west often is often dependent on spectacle/scale that Switch makes difficult to achieve (hence no MHW port). So like for like, PS5 is in a better software situation than PS4 was in the same period. We just have to wait to see whether the market (Japan) responds to it or whether PS4's audience has all moved on  or is unwilling to upgrade.

3DS is the third best selling platform in Japan's history so where as it didn't outperform the DS it out performed all other platforms before it with the exception of the GB which means it remains consistent in not only performing in the market but also retaining the position of market leader the problem with your argument is you're arguing comparisons can't be made because of market changes where as everyone is accounting for market changes in their outlook for PS5's possible performance. Nintendo made a move to tackle the problem with a hybrid form factor as a result they're heading for a possible LT range of 30m Sony have so far made no move neither hardware or software wise that really looks to address the issue.

On the WiiU comparison people compared platforms performances in their launch windows so when PS5 moves less than what WiiU did in the same time period obviously it's going to be a talking point, the whole point of the tongue in cheek doom comment someone made was the approach from Sony so far combined with a strong competitor steamrolling the region by a large margin at that is a position the brand has never dealt with before as even with the Wii and DS Sony at least were at the starting line with the competing platform while here the competitor is already well out the gates with multiple options still available to them to compete.

The PS brand's decline in Japan goes beyond just PS3 to PS4. PS3 was itself already a decline from PS2, and Vita declined steeply from PSP. It's a broader and longer term trend than just two systems.

To turn this around, PS5 would need to have something that PS4 doesn't, but PS4 already had mainline Monster Hunter, Final Fantasy, Dragon Quest, Resident Evil, basically every major Japanese franchise from third parties. What other killer apps are there for Japan?

basically the switch was a move to check sony into a impossible situation in japan, I have a feeling sony was going to make another portable if only for japan untill the switch came out.

the switch's existance means that any potential vita sucessor would either be only comperable or lesser in power to the switch, or it would cannabalize ps5 sales/ price point.

go market up again. First, take the vita/psp pipeline. 

You can just look at the Software figures since the launch of the PS4 and notice the trend, PSV might not have been successful but it sold close around 50 million software the majority of which was 3rd Party, this year the physical sales within the Famitsu Top 100 will be another sharp decline for the PS ecosystem and next year sales will decline further. Despite 2018 being the PS4 peak due to MHW it's still performed worse than 2017 which was the last year PSV got meaningful support.

1. PS4/PSV/PS3 2016 - 11.932.290
2. PS4/PSV/PS3 2014 - 11.199.346
3. PS4/PSV/PS3 2015 - 10.382.176
4. PS4/PSV 2017 - 9.462.066
5. PS4/PSV 2018 - 9.228.298
6. PS4 2019 - 7.181.200

Overall once it became clear that the audience of the PSV was transitioning to the Switch rather than to the PS4, it's basically ensured that a lot of 3rd Parties that were successful because they were able to have cross-platform games in the PS Ecosystem, will no longer be able to stop the decline of their franchises without prioritizing the Switch. 

3rd Party Top 30 PSV(with Minecraft)

1. Minecraft (Microsoft) - 1.095.680
2. God Eater 2 (Bandai Namco) - 397.994
3. God Eater 2: Rage Burst (Bandai Namco) - 342.983
4. Persona 4: Golden (Atlus) - 324.357
5. Dragon Quest Builders (Square Enix) - 292.125
6. Final Fantasy X HD Remaster ( Square Enix) - 281.475
7. Sword Art Online: Hollow Fragment (Bandai Namco) - 255.008
8. Final Fantasy X-2 HD Remaster (Square Enix) - 249.446
9. Toukiden: The Age of Demons (Koei Tecmo) - 237.361
10. Hatsune Miku: Project Diva f (Sega) - 227.492
11. Dragon Quest Heroes II (Square Enix) - 218.586
12. Sword Art Online: Lost Song (Bandai Namco) - 192.047
13. Kan Colle Kai (Marvelous) - 190.568
14. Jikkyou Powerful Pro Baseball 2016 (Konami) - 183.022
15. 3rd Super Robot Wars Z (Bandai Namco) - 166.095
16. God Eater: Resurrection (Bandai Namco) - 164.361
17. Phantasy Star Nova (Sega) - 161.154
18. Toukiden: Kiwami (Koei Tecmo) - 161.059
19. Senran Kagura Shinovi Versus (Marvelous) - 158.270
20. Mobile Suit Gundam Extreme Vs-Force (Bandai Namco) - 153.205
21. Hatsune Miku: Project Diva F 2nd (Sega) - 152.290
22. J-Stars Victory Vs (Bandai Namco) - 152.210
23. Sword Art Online: Hollow Realization (Bandai Namco) - 138.720
24. 3rd Super Robot Wars Z (Bandai Namco) - 130.600
25. Danganronpa 1 + 2 Reload (Spike Chunsoft) - 129.810
26. The Legend of Heroes: Trails of Cold Steel (Nihon Falcom) - 126.371
27. Tokyo Xanadu (Nihon Falcom) - 123.778
28. The Legend of Heroes: Trails of Cold Steel II (Nihon Falcom) - 122.743
29. Gundam Breaker 3 (Bandai Namco) - 122.181
30. Gundam Breaker 2 (Bandai Namco) - 121.971

TOTAL: 6.772.962

Top 5 Publishers

1. Bandai Namco - 2.337.375
2. Microsoft - 1.095.680
3. Square Enix - 1.041.632
4. Sega - 540.936
5. Koei Tecmo - 398.420

• Software 2020: 1.076.306
• Software 2019: 2.038.805
• Software 2018: 1.746.644
• Software 2017: 1.499.088
• Software 2016: 2.595.019
• Software 2015: 3.681.522
• Software 2014: 3.782.678

• Mobile Suit Gundam: Extreme Vs. MaxiBoost On (PS4) - 161.014
• Dragon Ball Z: Kakarot (PS4) - 149.654
• Sword Art Online: Alicization Lycoris (PS4) - 85.010

Bandai Namco is in a very interesting position. While it has provided decent support such Doraemon Story of Seasons, Naruto Ultimate Ninja, Taiko No Taksujin, My Hero One’s Justice 1 and 2, Captain Tsubasa, One Piece Pirate Warriors 3 and 4, etc. (not to mention helping Nintendo out with games like Smash Ultimate, Pokken DX, and the upcoming new Pokemon Snap), I feel they could do more on Switch with their more original properties.

I think it’s kinda too late at this point, but damn Soul Calibur VI on Switch would be awesome. Especially if they included a Nintendo character as a guest ala Link in Soul Calibur II, which led to the GC version be the best selling version. I’m not saying SCVI on Switch will be the best selling version at this point, but there’s potential for success here. If they’re concerned about completing the current dlc season, why not release a deluxe edition aka Jump Force? It basically had season one added to the base game while season two was under development. How did that release on Switch (choppy frame rates and graphics and all) before SCVI? 
Or DBFighterZ? How did that get ported so soon (less than a year) after it initially released on PS4/Xbone? It’s also an UE4 game like SCVI.

Or a new Tales of game. It doesn’t have to be Arise, but there’s potential to be had on Switch with JRPGs finding success on Switch such as Octopath Traveler, Xenoblade 2, FE:TH, the many FF ports, Disgaea 5, Ys XIII, Rune Factory, and DQXIS.

But I guess it all boils down to Harada, who doesn’t appear interested in investing more on Switch games. Just mostly ports or new licensed games and little else from their original franchises. It’s a shame, but it is what it is.

All what i am hoping from BN is to make a sequel to the jump ultimate stars game. With the 2D fightings, same story elements with same rpg compositions. That shaite was insane and a gift from god for anime fans.

Switch has the install base customers for such games and that will do really good on switch. 

A game like that wont cost much, Can be developed in a laps of 2-3 years and will sell well on switch.

But i dont know how third parties still want to make complicated stuff and develop High budget games when a small Idea Can bring a lot more.

And i still believe that bandai aren't making enough for the Switch like all the Big japanese third parties ( except Capcom). Ports are lazy stuff despite all the efforts they Can make to do them.

Supposedly better shipments for Asia from January

Agreed. Many say - and rightfully so - that Sony doesn't need Japan to sell it's hardware. That is true. But the overlooked part are the smaller japanese third-parties. Many point to Capcom, Squenix and Bamco, but Japan has (in difference to the west) a more or less working environment of smaller and mid-sized studios. And these are losing their confidence in the PS ecosystem. We see that with a lot of titles that now move to Switch and PC (should not be discounted). The success of Momotaro Dentetsu is another building block strengthening the confidence of japanese third-parties in the Switch platform. And here is the trick: although the main market for these games is Japan, they also have western fans and this is filling the lineup of the Switch.