Post any thoughts/speculation about what may happen in these last few episodes! Here's my guess:
The Intersect starts destroying Sarah's brain. Time is running out as the team must decide whether to pursue Quinn or try and fix Sarah immediately. Sarah decides to take down the bad guy first, but after they do, the damage is irreversible. They are able to remove the Intersect from Sarah's brain, but in the process she loses her memory, forgetting everything. Chuck has to reintroduce himself as her husband and help her remember everything about her life, but he leaves out anything to do with her being a spy. It's to protect her and to make sure they can lead a normal life.
I actually hope this doesn't happen. It would be so sad to see Sarah so clueless about who Chuck is =(