Dont agree, I used "second machine" between "" because it can be read in multiple ways, but what I mean is that it is very probably that many will have Rev as well as a XB/PS but not prefering one or anouther then the money gaming will depend on the gaming offering like exclussives/games overall or in the case of multiplatforms (assuming that there will be) controls/features/price... So if they can secure good games (it seems they have a lot of theird partys interested) I think they will have as much money gaming as the "prymary one".
After all I own both GC and XB, but the only reason I buy more games for XB is because they have more exclussives and the multiplatforms games are better on it (HDD, gfx, online if you want...) , but I really (if specs are enought) I dont see reason to that happen for must people this time.
Plus there will be many that will have only the Rev, specially if they can indeed get new gamers.