Depends on how any other two perform.
If both the wiiU and XB1 never reach their peak monthly sales numbers, then it will kinda by default mean that teh PS4 will not only reach those numbers but exceed them. If everyone isn't buying something, its cause they are buying something else.
lets say in fall 2015 both the the XB1 and PS4 are at $300. And that also happens to be when all the big multiplats are exclusive to current gen consoles. And that also happens to be when FF15 comes out in japan/MGS5. And that also happens to be when halo 5 and uncharted 4 release. Lots of ifs I know. Well, it will take all these ifs happening for either the PS4/XB1 to exceed their PS3/360 monthly best. It will be impossible for the wiiU though, I mean the wiiU hasn't managed in over 18 months to sell what the wii sold in one month.







