I'm sure Bard will give a more detailed answer to your question but to sum up all SKU's utilize the same game engine (a twice updated, at least, form of the Modern Warfare engine) and Wii modeling is just a truncated final model for the HD SKU's, it should work and look quite well.
On top of that, if Treyarch are handling the Wii SKU then we already know what they are capable of and with that experience under their belt I'm certain they can do even better this time around.
A thought has occurred to me. It's a long shot fellas so don't bank on it. Recall that WaW on Wii never received any DLC because of the original internal memory limitations. The Wii SKU was never designed to have DLC so even AFTER System Menu 4.0 with SD access was released, Activision couldn't push Treyarch into DLC because that money, time and resources were never planned for it.
What I'm speculating as a potential hold up is Activision realized that they could implement DLC into the Wii SKU of MW2 so development had to be put on hold while the specifics were planned out which if you time things up would mean they couldn't announce the Wii iteration alongside the HD SKU's because things on the Wii side were still changing and being finalized.
It's on the extreme end of the plausible stick but I'd sure like to be right about it.
The rEVOLution is not being televised
