PS4 is solid first. The question is by how much, and in what regions. Wii U has a reasonable chance in Japan of beating PS4. XBO has a reasonable chance of competing with PS4 in US and UK, though at this rate I feel like it'll end in a statistical tie at best. I still think there's a small chance of Wii U competing with XBO, though it's certainly looking like it's a matter of just how much it will lose by at this point. Really, I'm just glad that Wii U made enough of a comeback to have a normal Nintendo console lifespan, and it's surprising enough that XBO has competed with PS4 for this long.
That said, generations never seem to turn out quite like anyone expects. Let's just wait until something interesting happens, because it will, even if it changes nothing in the rankings in the end.