Acesonnall
It's kinda obvious.
Although, i'm not sure whether wii u will be last or not, it depends on how bad microsoft will do, and how well nintendo, but i'm sure that they will be closer to each other then ps4 in reference to anyone, i think ps4 will sell more then wii u and x1 combined, look at the charts, polls etc..
And gap between nintendo and sony-ms is still pretty huge, so nope, even if devs will come back, wii u won't be multiplatform console.