There's some motivation to get me drawing again. Too bad I still can't shade for crap, but at least I can do competent flat-colors... *sighs*
Im certain it wont be ALL fanart. Plus Udon knows their stuff. You wont find a Girla type scribble for example. And some of Udon's artists are Megaman Fans themselves, so im certain there will be Udon art there too.
Udon often strikes me as having a strong tie with the MegaMan fanbase. Correction of "Rock" in the Powered Up! page of MMOCW being a major point, as well as their use of traditional X5 Maverick names. They also maintained the use of "Force Armor", although that one's technically incorrect (the fans keep it popular because it sounds cooler).
And actually, I can see that in the way that they arranged the cover-art. First of all, you'll notice it's all the "platforming" MegaMen and not the "chip collecting" ones ("legal reasons", eh?). Second, the "triangle of focus" in the image is clearly Rock, X, and Trigger, the original "big three" series of the franchise, with Zero/ZX characters given lesser emphasis.