I would hardly call it wishful thinking, no one knew what Wii was at that time, and any sane speculation wouldn't of assumed overclocked gamecube was the answer. Anyone assuming overclocked 360 this time is using some form of wishful thinking.
"a good deal on parts?" an embedded GPU would be cheaper than any desktop redesigned part from R700. I do have a question here since you've sort of run into a dead end, what exactly is a r700 feature set? how is it different than r800 or r900? sm 4.1 instead of 5? DX10.1 instead of DX11? where did you get that info from? early dev kit spec sheets are not written in stone, they don't tell the future, only what is currently available. It's not even a target spec list, but actual hardware that was in early dev kits that were out just before the launch of the embedded chip a lot of people are currently speculating on.
The little we have seen from Wii U, suggests at least 1 DX11 feature is being heavily used in games like Pikmin 3, Zombi U, p100. That feature being depth of field, sure it can be faked even in current gen and to a lesser extent scripted into the Wii like in last story (as lost in blue pointed out on gaf) pikmin 3's effect doesn't look like tiling blur effects, it looks like true depth of field we saw from stuff like the lady bug demo for R800. When stuff, no matter where it is on the screen gets to a certain distance, it blurs automatically. While that can be faked, it should take a larger performance hit than it would in DX11, so why are all these devs using it unless it's relatively free?
I'm not sure why you are holding on to early dev kit specs, the "PR" about 2012 bells and whistles comes from a dev on neogaf who works with the Wii U named Antonz, and Kotaku's article about a weak CPU a month or so ago still pointed to DX11 features but with DX9 performance. (whatever that means, as e350 is a DX11 gpu with only 80GFLOPs and highly outclassed by xenos in terms of performance)
So what exactly about using a 576GFLOP GPU seems impossible to you? I don't think developers doing ports for instance, are really going to have a good grasp of the actual hardware, dumping their 360 code directly onto Wii U will work (Darksiders 2 was up and running after 5 weeks, so we pretty much know this is being done) but it will be highly
inefficient, I could see devs not finding a lot of room to bump stuff up more than 50% if this was the case.