Sony should get its own exclusive new IP that will do amazing in Japan. Nintendo had Splatoon and Yokai Watch .

Well, the best platform to play Monster Hunter will be the PC, followed maybe by the XxX.
The PS4 will be at best, the second worst way to play Monster Hunter World.

Also, I am not sure Level-5 wants to jump ship for a platform that only has about 5 times the install base (In Japan, as of right now) and much less of their fanbase.

You cannot take the PS4 on the go, and that is a big selling point for Japanese consumers.

I don't think it will come to the PS4, or if it does it will also be on the Switch and will likely sell better on the Switch.

Knack 2 >>>>>>Pokemon,YW,MH,DQ

I never said exclusively. If it's worth devs time porting games to switch that sell less then 200k then it's worth giving this a ps4 port. 

So, Yokai Watch isn't a Nintendo IP? I thought it was this whole time. In any case, I think it'll stay with Nintendo.

The game was announced in december 2015, and had probably been in development for quite a while before that. Probably the Switch just came too late.

There is also the fact that porting YW from the Switch to the PS4 means porting from weaker to stronger hardware, but porting NNK2 from the PS4 to the Switch means porting from stronger to weaker hardware, which presumably requires more effort.

hard to say, at november level 5 will release ni no kuni 2 for ps4, if they make something other for the ps4 i think it could be a completely new ip

I think it's possible, though I wonder if Level 5 would need to deviate outside of the 3DS and Switch in terms of YW. The targeted audience are mostly kids, which the 3DS and Switch seem more suited for them. I figure kids would prefer those consoles over a PS4.

It's not Nintendo exclusive as it is.  The game is on mobile and level 5 are placing a much bigger emphasis on those platforms going forward.