The trend for certain games was cemented even in cases where the userbases were not in one company's favor, like Metal Gear Rising on PS3 in America, PES on PS3 in UK, or Splinter Cell on 360 in a number of European countries. It isn't just that one side gets accustomed to that brand, the other side may pick up other games in the meantime and grow attached to them, making that brand not mean as much to them. For example, Destiny might become much bigger on PS4 thanks to the TItanFall/Halo vacuum.
Edit 2: I fully expect Metal Gear Solid 5 to sell better on PS3 than on 360 or Xbox One in the US.
Of course the game will sell more total if the PS4 is in the mix, but getting the first edition (even if it was just a timed exclusive, which TF doesn't appear to be) has traditionally been a strong indicator of future franchise success on that platform.
Edit: GTA is cross-generation, and a bit of a poor example. The previous GTA games all appeared (and sold well) on the Xbox, albeit they were all timed exclusive on PS2. There was no reason for GTA owners to upgrade specifically to PS360 until after the game was out. The Xbox One will have at least one year as the only next gen platform to play TF, so it will have existing XOne owners as well as most upgrading 360 TF owners in that time (most people won't be aware that a PS4 version is in the pipeline).