I feel he may well remain as a MP for a while after he leaves the office of PM as they will guarantee him media time in the UK.
After a while though I suspect he will spend more time of lecture circuit in the US.
Eventually I can see him in the Lords though following the traditional route of ex PMs. I think he will love to have a title one day.
Just reading what Blair might do after leaving his PM job...and all of the different options, I really think that Bill Clinton is probably very envious of his friend Tony...
Because I am sure that Clinton would love to have a system here, where he could go from POTUS to a LORD!!