Crist would have had to defeat a potential tea-party challenge in the GOP Primaries, probably from Rick Scott. Crist probably wins renomination, though by a somewhat close margin considering that he hugged Obama (the horror). In the general election he faces off against someone like Dan Gelber, but not Alex Sink who runs for the Senate (as it becomes the easier contest). Crist wins reelection by a fairly wide margin and becomes a potential 2012 Presidential Candidate from the more moderate branch of the party (think somewhere in-between Giuiliani and Huntsman).
In the Senatorial contest, there is obviously a vacuum for centrist Republicans that needs to be filled. This is done either by the candidacy of Adam Hasner, Bob Smith, or Joe Scarborough. Regardless, Rubio still wins the nomination. He goes on to face Alex Sink or Debbie Waserman-Schultz in the General Election. At that point it becomes a very intense race, with Rubio narrowly prevailing due to the GOP wave.