It might take the lead for a week when MK releases but that's it in my opinion. As for taking back the lead in the gen; that one is quite simply impossible, with the gap between the PS4 and Wii U likely being quite large by the time holidays set in, the Wii U would likely need to sell at least 6-7 million during the holidays in order to take the lead in hardware sales. It sold about 1.6 million during the holidays last year (beginning of November and till end of December). A 650-750k average or more during November/December seems incredibly far-fetched (best week last year was 350k-ish). Unless it sells bucket loads in the months leading up to the holidays, which seems equally unikely at this point.
I have no doubt that it will improve upon 2013's numbers, the numbers in my sig would indicate as much, but thinking it has any kind of shot of actually taking the lead is quite simply fantastically unrealistic under any possilbe circumstance. It would need to increase probably around 300% or more year-over-year for any chance, perhaps more, and we know that since it has been slow up until now; that leaves most of that increase for the latter half of the year.
Predictions are cool and all but this is simply impossble.