Well, I can't say much about that comparison. I haven't played NnK, let alone Yokai Watch.

No reason to keep it only on Nintendo platforms if their going to target the Switch with it's low install base when PS4 is much more mature and has far better reach in markets outside of Japan so sure why wouldn't Level-5 take the opportunity ?

By the end of next year PS4 won't be too far off 8m in Japan. Should they ignore such a large userbase? A mainline Yokai Watch port on PS4 would sell 500k I'd guess. Maybe even more, who knows. But the cost of porting it would probably be worth it for the sales it would get in Japan/Asia and the west.

Today they announced that ps4 would get a version of the next inazuma eleven. This was always a franchise in recent years, like yokai watch that was heavily Nintendo biased.

It's also smaller then yokai watch. If level 5 are making nino Kuni 2 ps4 console exclusive and inazuma eleven multiplatform including ps4 then surely a yokai watch on ps4 isn't beyond the realms of possibility?

DQ 11 and mhw both did great on ps4. Imo it would be a mistake to not at least give YW a chance on ps4.

DQ and MH both began as console titles. Most main DQ games are console games. Monster Hunter sold a lot on portables because Japan but it never seemed like a portable only series esp as some of the games were ported to consoles. Wii and Wii U and now Switch with XX. Yokai began as a handheld game. It's tailor-made for a mobile experience. Honestly if one was made for a console the only one that makes sense is the Switch as it doubles as a portable. No one really thought MH or DQ can't sell well on a console. Yokai being portabe is one of the main points of the game and I mean in game itself. If you really want to play the games then get a 3DS. You can find some of them pretty cheap and the system has plenty of games even 3rd party to justify its purchase. It's possible to put YW on PS4 but I doubt is worth the effort for them when they have it so good already with no risk at all.

I can't see it being on PS4 tbh

I agree. No hurt in releasing a multiplat for Switch/PS4. Maybe even still include 3DS, after all this is there the base is. But generational jump has to be done anyways, so why not put it on all eligible platforms and look how it sells on each.

Level 5 will keep it safe and low budget. Handheld only is my prediction.

Inazuma eleven is a franchise that peaked a long time ago, so it makes sense to spread it out to more systems, at least until the Switch version comes out which is a given. However, I don't think it's comparable since it doesn't have the Pokemon factor like Yokai Watch has. I remain skeptical.