Collins doesn't strike me as a lifer, so when she retires the Dems will probably pick up the seat. Is it conceivable that the Maine GOP finds another politically adept moderate with enough crossover appeal to win a Senate seat? Sort of like how Collins won in the first place. 
Or is Collins a unique product of her time and the time when Maine would give a non-incumbent Pub a Senate shot has passed?
I'm not sure. She has never missed a vote, so it wouldn't surprise me if she tried to beat Grassley's record!
