IF Wii U is only PS3/360 or moderately more powerful, and PS4/720 are vastly more powerful, how economically feasible will it be for developers to support Wii U with the latest versions of current gen engines and tools? Isnt it going to be significantly expensive to move to UE4 and its contemporary competitors? Won't it be economically viable for some developers to stick to what they already have licenses to use? I imagine the cost of creating assets for UE4 level visuals is going to break the bank for a lot of already struggling studios.
It will depend on the developer/publisher. EA will more than likely be utilising, and iterating on, Frostbite 2 for the start of next gen. There will also be those who use engines exclusively designed for the new platforms, though I think that will be limited to a select group of the "top tier" developers. I think it will be a while before you see widescale adoption of UE4, basically, and instead you have Bioshock situations where companies are taking the engine they use currently and doing minor iterations on it to have it fit their needs, specifically in terms of the rendering engine to take advantage of what the next generation will offer.
Cause another thing a lot of devs are saying is they don't plan to throw out and totally rewrite their complimenting systems (physics, AI, etc) anytime soon. It just takes too long to effectively start from scratch. Same goes for the internal development tools companies have built up over the course of the generation.
Given sales numbers, I find that surprising.
Not talking about sales numbers, but their initial development background. Aside from the number of developers who started on the PC but moved to consoles, which this generation is honestly too many to name, anyone becoming a graphics programmer is going to be trained in the use of modern graphics architecture, which the Wii didn't have. This generation saw a definite shift away from the unique architectures the platform holders would devise for their new console, towards something more standardised. Hence why so many developers prefer using the 360 SDK, and why so many had trouble with the PS3.
It also ties into why Western developers have been so far ahead of Japan this generation, both in terms of the number of high quality games produced and the technical ability shown by the teams.