I feel GSP has plenty of challengers at 170, and seems he'd prefer to stay, rather than move up to fight Anderson, and then as he's said, need to stay at 185 for the rest of his career.
Rory is a great fighter and could easily be a title contender, but if he won't fight GSP, than why stay around and just be a wrecking machine for no good reason?
Therefore, I feel Rory would be more likely to move up in weight. And it'd be sweet!
Although there are tons of good fights at 170 for Rory....So perhaps he sticks around at WW anyways.
I'd like Rory vs. Erik Silva or Rory vs. winner of Fitch/Maia.