If Rubio ends up backing an immigration bill favored by Obama, it will become extremely difficult to prevent a conservative backlash against him. So it’s possible that Rubio is the one trying to play both sides of the issue, and he may end up succeeding. It would suit Rubio’s interests to make some effort to promote Bush-era legislation, which earns him favorable coverage from non-conservative media and boosts his reputation as a “reformer,” but then become an opponent of whatever legislation comes before the Senate. Rubio will say that he wanted to make a deal, but the other side was too unreasonable in its demands. That way, he can neutralize most of his conservative critics while retaining a reputation for “bipartisanship.”
Is Rubio that cynical/canny of a politician? Maybe not, but it wouldn’t surprise me if it turned out this way.