I used to pretty much agree with you, except it was one term, and NO government position for at least a year before election (IOW, no getting paid to do a job while being a full time candidate). Now I'm thinking ONE term and out.
That way you screw up plans of career politicians but can regain a good congressman the majority of the time.
How many real keepers are there? I'll bet there's enough great people to replace them. Besides, lots of people think Kennedy was one of the ones "we" needed to keep.
Of course, the system would have to be radically changed, with things like seniority out the window. It'd have to be much simpler so that it wouldn't take a whole term just to learn how to play the game. Sounds good at first, but then they'd have more time for doing their real job (maybe we'd need to shorten the sessions, which is a great idea anyway -- do we need so many freaking laws that these people need to be in DC most of the time???).
One problem with term limits, especially ONE term, is with no "need" to get re-elected, there's nothing to keep them beholden to the interests of the people they represent.