Actually, World at War and Black Ops on Wii got quite good reviews.

They may not be beautiful, but the Wii COD games still function. That's the question here, how can you port despite RAM disparity. The answer is, by making sacrifices to things that don't comprise gameplay, like texture resolution and detail.

It's just like playing a PC game on low settings. Wii U will be able to handle most next gen games, just poorly. Further along however games will get to complex for it to be even feasible to down port. For example the best games today simply wouldn't work on Wii.

No, it's a perfect example on how an engine looks like on weaker hardware. It was still the same game though.

fair point, i'm just curious if a game that uses more than 1GB with all that power we might see more complex games with realistic AI, detailed environments, fluid animations, how will the WiiU be able to perform those and still be playable?

Yes, that's the question, but keep in mind that all future engines are built with having a wide variety of targets in mind. From smartphone to high-end-pc. *How* this will turn out we have to see :)

Seeing the games we have now this will not be a problem for years. Most games won't even use all the ram ps4 has for the first couple of years. And Nintendo is the one who makes their games shine on their systems. So things are not as dark as all these doom threads keep making them out to be.

Well, WiiU of course lack the processing power/graphics capabilities and amount/speed of RAM of PS4, and multiplatform games on WiiU will be downgraded on the Nintendo Console compared to PS4/X720. All future multiplatform games will be conceived with PS4/X720/PC in mind, with PS360/WiiU getting a very downgraded version. Also, I noticed that many 3rd party devs don't consider a lot WiiU, as happened with Wii also. After GameCube, Nintendo are just releasing "next gen" system which are sligthly more powerful than previous gen.
I miss so much the Nintendo64/GC era, damn you Nintendo !

I am curious about this scaling. Could a game like Skyrim be possible on Wii? If so what sacrifices would need to be made for the game to be played on it?

It's not just about the resolution of the textures. There are all the aspects of much more advanced AI, scale of the world, framerate, loading times and their frequency, etc.

Wrong ! Starting from next year, many 3rd party devs will start to use more and more of the resources of PS4/Next XBox to have similar multiplatform games VS high end PC.   PS360 and WiiU will get a heavily downgraded version, that's all.  PS4 and the Next XBox, again, will be the main target of most 3rd party developers/publishers.