I believe Apple will do everything they can to keep them from abusing the ToS, but I also believe Facebook will try to work around any and every restriction applied to them.
Yeah, well, but Apple can always reject apps that violate their ToS, or revoke keys used to work around that. So ultimately Facebook can't win.
Except if they force Apple to nuke all of their apps, which would put Apple in a difficult position. But perhaps Apple could sandbox apps, and prevent them from doing stuff that violates ToS.