I think Arkam really helped any speculation we could of had, it means 1TFlops is off the table, especially if people think an HD6670 is the base for x720, I will stop speculating with hard numbers, but something based on one of these types of GPUs would have half the memory bus (128bit) in Wii U it would be a low clocked part with maybe twice the Gflops in early dev units, but it would have modern shaders (with "plenty of features" that arkam is talking about and yet have "no teeth")
That is exactly what trinity is, Nintendo did happen to patent Triforce again, maybe they will use it for the code name of their GPU, to be honest this would put the hard numbers around 2x the 360 and I'm ok with that.
I think you're holding too hard to the 6670 aspect of the rumor. The 6670 isn't that far from a TFLOP, they could have started with a base 6670, die shrunk it and upped it's clock. Plus it's said to be 6x Xenos, which if I remember right is what a .24/5 TFLOP part. 6x would get us around 1.5 TFLOPs. If that's 20% faster than the Wii-U GPU that would give us 1.25 TFLOPs for the Wii-U.
The problem here is that we're speculating with rough estimates that we don't know their exact meaning. Is the 6x number DIRECTLY referencing it's G/TFLOPs, or is it some arbitrary number being thrown out.
Is the reference to the 6670 supposed to tell us it's shader cores, or is it more saying it's based on a Turks chip. We don't know how that chip has been customized. What would they have if they took a 6670 Turks chip, shrunk it down from 40nm to 32/28 and upped it's clock from 800 to 900 or 950?
Or is your assumption right and we're looking at sub 1TFLOP peformance for the 720 and Wii-U? A straight up 6670 would give you 768 gflops and the low end of what was rumored to be in the Wii-U dev kits would be like a 4830 would give you 736 gflops.
I think until we have solid info on clock speeds, shader core counts, and the like, try to speculate hard number performance out of the info we have is too difficult. There's too many variables, and too much else we don't know.