Here is how I see it:
CPU centric games:
(taking the gamepad and Miiverse into consideration.)
-Without optimization, developers can quickly port and run current gen AAA games on the WiiU with some hiccups in frame-rates, loading and a few other things.
-With slight optimization they can add higher textures.
-Fully optimized the WiiU can take those same games with higher textures and run them at higher resolutions (sub HD to 720p 30fps) , steady frame rates & no tearing. So you get cleaner, more vibrant looking games.
GPU centric:
If developers would design the games around the WiiU architecture.
-They can can run those same games at higher resolutions, and higher frame-rates with no tearing. (ex: 1080p 60fps)
-They can run AAAA next gen games at lower resolutions (Sub HD or 720p 30 to 60fps) and a steady frame rate. By the time we see games like this come out, it will probably be mid to late 2014. Depending on which developers are still around.
But, how many AAAA games will we have next gen? And how many will be multi-plat and not first party exclusives? Most likely, the majority of the games will stay within the same budget ranges as this gen, with enhancements the WiiU is most likely designed to handle.
Conclusion
the CPU and memory is good enough to handle current gen games.
Which is what Nintendo wanted this first year.
Nintendo appears to have put their money into latencies and utilizing advanced memory controllers to offset memory bandwidth restrictions. So Im not seeing the memory as being a bottleneck. The bottleneck are the publishers who decide the money, the budget and quality of the team working on ports, and games in general.
Then again, Publishers can also decide in the future to use WiiU as a base, and cheaply port games to the Durango and PS4. Because if those consoles are that more powerful than the WiiU, they should run games made on the WiiU with no problem. Which means visual and performance differences between WiiU games and future consoles will be minimal. But this will be based on the target audience install base WiiU will have by E3.
If games like Bayonnetta2, ZombiU, CoD and other perceived core games, sell well on the WiiU, publishers will not treat the WiiU like the Wii. They will see it as a potential PS2.