Does. Not. Compute.
The point is not that the franchise will likely be in some form on Vita as well, the point is that the franchise is not a portable Sony exclusive anymore, and even more relevant to the market is that it's going to be on 3DS *first*, and enthusiast now even know that they'll keep getting new iterations with an already announced MH4.
What was responsible for single-handely shifting the PSP's fate from zero to hero for the japanese public and what would have been a trump card for Vita as well, just got wiped away... Do the math. Capcom's telling their fans to get a 3DS, plain and simple.
No longer a choice to be made on whether to go for Nintendo's games OR for Monster Hunter. Now you have a platform that has everything in a package, Mario Land, Mario Kart, Animal Crossing, Pokemon, Monster Hunter, Kingdom Hearts... Basically only Square can now put some real weight behind the Vita now with a mainline Dragon Quest (totally unlikely, seems Nintendo got a lock on DQ and its relevant spin-offs) or Final Fantasy (probable). Even in the case of the most positive TGS outcome Sony could ever hope for, there's nothing they can do anymore to properly counter that unstoppable march of the franchises-that-matter,