Game engines like Unreal are inherently scalable. That's the beauty of these beasts. Unreal 4 is made to be as scalable as possible (it can run on HTML5, mobile, consoles, and PC--all these platforms have very different needs and capabilities, but Unreal manages). To say they would have to strip out features shows a lack of understanding. The proper term is they would have to scale back on features. Textures may not be able to be 4096 x 4096, and you may not be able to run at 1080p. However, I'm sure that most features of Unreal would be able to be implemented on the Wii U, especially considering it has DirectX 10.1 level features.
To clarify, it may not support hardware tessellation and other features that are necessary for the hardware to support, but anything else, it surely can. In fact, because the hardware is accessed at a much lower level on consoles than on the PC, a developer could very well implement features not natively supported. This is true especially so with GPGPU technology. For example, Microsoft's DirectX feature set on the Xbox 360 has features not present on a consumer-level equivalent card. I believe one of these features is multisampled render targets.
So, while Epic may not be porting Unreal to the Wii U, it does not mean that another developer has to port a bastardized version of the engine. On the contrary, it would just mean they have to scale back on things like textures, resolution, etc.
