Capcom ported RE4 to cellphones, I wouldn't be surprised if they decide to make a Wii version.
Oh sure, I wouldn't doubt that they COULD make a Wii version.
I would merely ask, what would be the point? It most certainly wouldn't be arcade-perfect, thus already doing a lot to invalidate a need for such a version right off the bat. It might as well be marketed as a different version of the game, even more so than the likes of Capcom vs. SNK 2 EO was from the original game.
So, in the end, it's the same thing to me as it is with beggars/whiners asking why Tatsunoko vs. Capcom is Wii exclusive: in the end, if you really want to play the games, as they were meant to be, you find a way to obtain the means to do so.
With SF4 being made available for PS3, 360 and PC, there's a good deal of options available, I would think.