Hope Reggie makes good on that promise. Given how it seems the CPU and GPU of the Wii U is similar to Xbox 360 counterparts, I would imagine that we needn't worry about lesser versions as was the case with some multiplatform Gamecube games.

At least as good is the very least I would expect.

Most games of that time were brought down by the PS2, not the GameCube. It wasn't until developers really started using the extra power of the Xbox that you saw tiered graphics between all the consoles.

Yes. From what I understood at the time, the three home consoles had their own special hurdles to surpass in development. While the GameCube was reportedly easy to develop for, the platform picking order had the PS2 at the top and GCN at the bottom which meant that the GCN version usually gets the least optimization.

I found that usually the Gamecube only got the weakest version as online play became more common.  The Cube version would then always be the worst because it would be lacking the online mode the other versions had.  For offline games the Cube versions usually were fine.

Well it doesn't surprise me that they used the other console's footage for the Wii U. The developers already have a working and stable engine for those consoles so it easy to working demo playable or not. And from what I have read the two games that were running on the Wii U hardware were ruff around the edges. So it would look better to use the footage running on the other consoles.