I'm pretty sure they've already cut multiplayer, so this is all a moot point anyway. However, the implementation of the skylines wasn't the reason it was cut. I still don't really understand why you think having rails in a multiplayer game is something only a PC could do when there are plenty of console multiplayer games that feature much more demanding physics calculations.
This isn't a debate over whether or not console multiplayer games are good. It's about the technical capabilities of consoles. For example, if it was announced that Rome 2: Total War was going to be a multiplatform release, that would be a genuine reason for concern because the Total War games are very CPU and GPU intensive. Consoles could not feature as many units while maintaining a decent framerate, so the scale of the game would have to be toned down. Supreme Commander 2 is a good example of this. The skylines in Bioshock Infinite are not GPU or CPU intensive so they are not reason for concern.