Wii U is 8th gen with (much) less power.
With IBM Power, far less power and so on ports of big AAA games are difficult to impossible. But there would be at least some ports or special versions if Wii U was selling better and the Wii U crowd was buying third party.
Which in the majority they are not.
And that is the basic point Ian Bell made in the WMD forums. They'd have to make some major cutdowns. Wii U version could not be in leaderboards etc. because of those differences. Basically it wouldnt really be the same game.
And he asked the bad economic question. How much will that cost, who is gonna buy it in the end? And is that what anyone wants from Project CARS?