Wii U will probabally sell around 240k globally.
I expect the X1 to sell around 600-700k, so I guess it is quite possible.
Looking Foward, October will be full of games like Forza Horizon, Sunset Overdrive, Project Spark, & a bunch of Multiplatforms, so expect the X1 to win again by about 200k+, and in November, it should continue that trend with Halo MCC & Cod Bundle out to sell 300k+ more than Wii U. (which means it will have closed the gap by about 1M by December.)
Now I don't really expect it to do much better than Wii U for the Holiday as the Wii sells really good for Christmas, and Smash Bros. will make a big splash. I think they will do about even for December which puts X1 about 1M behind Wii U going into next year.
Who knows though, anything could happen. I honestly hope they both do great!
