The right question is: is capcom about to close enough to make a MH5 for vita?

LOL. I'm sure it would be magically a better game for you if on Vita.

Even an upgraded MH4 Ultimate type game would net them some major cash on Vita. Unless they have a contract I don't get it either.

In mid-gen, I doubt it, too dwarf installed base.. If it was in the begining it could have been a smart move.

I think there's no chance Monster Hunter will move back to the PSV

Supreme fix, just for you

It would help the Vita but the sales of MH on 3DS would be much better, making Capcom want to continue their exclusivity with Nintendo

Nope not happening.

The whole point of MH is it has to be on one platform, if you split the fanbase then you split MH's core pont of success ... the local ad-hoc multiplayer that is extremely popular with Japanese kids. You want all of them to buy the same platform so they can all play together. 

Besides the 3DS has a far, far, far larger userbase and the game's sell great on the 3DS. There's no reason for them to change.

Unless Sony pays part (if not all) of its development, they won't make it for the Vita. MH already has a dedicated fanbase on 3DS. The sales boost would also affect only Japan, MH4 is coming to 3DS to the west.

The monster hunter fanbase moved from PSP to 3DS pretty smoothly. So the only real question is whether the fanbase would be too pissed off at having to buy a Vita in order to play the next MH. If the fanbase is reasonably well disposed to following the franchise to a new platform then there's unlikely to be any sales lost by shifting. 

RE: R2 is not that huge for PSV unfortunately, it will take something big like MH to substantially change PSV fortunes.