Think P5 will hold up against that finish sprint from P4?

Wow indeed! 

Is splatoon the most selling home console game this gen in Japan so far? 

Nothing comes close. It even outsells 3ds games not named Pokemon/MH/YW/AC and some Mario games (abd smash)

Fanbase of tales of still on ps3?

Persona 5 and Tales of Berseria have high chances to surpass their predecessors. This kills the excuse that console gaming is dead in Japan. It's just that FFXV is not appealing.

Even though it's going to outsell both combined? lol. fluctuations are fluctuations, all IPs have them at different times. Selling more than the predecessor (and if Berseria does that it's only because Zestiria didn't have a PS4 version at launch. in fact both games have the benefit of being on two PS home consoles while their predecessors were not) doesn't mean anything if we're not talking about high numbers

http://www.neogaf.com/forum/showpost.php?p=210049668&postcount=160

First day sellthrough {2016.07.14}

[PSV] The Legend of Heroes: Trails in the Sky the 3rd Evolution # <RPG> (Kadokawa Games) (¥5.800) - 50-60%
[PSV] Uppers <FTG> (Marvelous) (¥4.980) - 30%

More like Downers, amirite

What reason is there to upgrade for them? The best JRPGs are on the ps3 for them. 

Well, the majority are on going to be PS4 purchases, but Namco only have themselves to blame for slow adoption. I believe that Atlus wanted to wait until after FF15 to get a lot of mainstream JRPG fans over to new platforms.