Wii wasn't more powerfull than xbox 1 was it??
Given that the gamecube was sometimes capable of visuals comparable to XBox 1 and the Wii is "1.5x-2x GC", I'm pretty sure it is.
The main CPU may have comparable performance between the two, both have a dedicated 3D positional audio processor, but the Wii has an ARM9 to take care of all I/O (controllers, optical drive, etc) and encription/decription functions, so in the end the Wii should win in CPU power.
The GPU should also be a bit faster though maybe less flexible (some say the TEV units offer similar functionality to the DX8 shaders in the NV2A), even if we look at raw numbers from Flipper and multiply for 1.5.
But in the end, memory performance should be a lot faster in the Wii.
The XBox 1 has 64MB of UMA. The Wii has 3MB eDRAM for texture/framebuffer, plus 24MB of 1T-SRAM in the GPU, plus 64MB of GDDR3 for system memory.
Nonetheless, the Wii is considered a "late 6th-gen" console, essentially capable of late 6th gen visuals, but it's still the fastest of the bunch.
If the Wii U comes out and does
less than the 7th-gen consoles, then 3rd parties won't even look at the console for anything other than cheap ports during the first 2 years and cheap casual games for the rest of its time -> which is the main problem Nintendo says it's avoiding this gen, so it really doesn't make sense.
Even worse is if the new XBox practically copies the tablet controller from the Wii U and attaches it to a modestly powerful console (Juniper level GPU, for example), all while selling at the same price as the Wii U because Microsoft is willing to sell at a loss.