"Up to now"? This is even less plausible than it was a year ago.
I'm always open to the possibilities of a third party game to "shift" platform.
As I said, this is the "weird" scenario, not so plausible at the moment.
This doesn't make sense to me, obviously if you are the higher seller platform of the generation you don't need many moneyhat, if nothing strange happen, like with the Wii. But with both the Wii and the DS Nintendo didn't actually killed the PS3 or the PSP like is doing with the Vita. In the past generations it was different because the distant was so big with the other console (Probably the 3DS can repeat that). However the third party situation of the DS was really different than the Wii one. DS got a lot of exclusive and so is the 3DS obviously. Even more in the future judging by the Vita numbers. If you think about it before the 3DS and Vita come out, a developers can actually choose both of them watching the success of both DS and PSP. With the Wii U is a little different because Wii wasn't really as succesfull as the DS, for a lot of reason, not only Nintendo related, and the PS3 is still there.
It's seems strange to me that Capcom spent money on porting the game to Vita and after the game is playable decide that it want to keep the fanbase focused.
As I said, we don't know for sure which was the status of this rumored MHP3 for Vita. Could have jsut been the PSN title compatible with Vita, to be played with dual analog sticks.
That said, I still think that is absolutely legitimate to imagine Capcom to choose 3DS on their own for their most important Japan-centric brand.
I know that PSP was great for MH and Capcom, but with 3DS coming on the market before Vita, with the 3DS now able to "play" the game hardware-wise, with the DS setting records over records in Japan, considering how the portable market was/is strong over there, considering how MH is Japanese-centric, it make perfect sense.
Also because of the possibility to not totally upgrade the assets of the game itself, continuing for another generation (the 3DS one) with the same re-worked assets.
There is no evidence of a moneyhat by Nintendo, apart the incentives (like the Circle Pad Pro and a possible partnership about western distribution) already discussed.
And this will be even more clear when (and they will: the only console without MH was the DS for hardware limits) they'll spread the brand on all the consoles availables (of course with projects of different nature and importance)