Well Pierce is my favourite Bond, and I've heard that he will do #21. After doing The World Is Not Enough he said that was his last, but then he did Die Another Day, and after that he said no more, so it could go on for a while.

He was actually aproached for the role in the 1980's, but felt he was too young at the time and refused it, hence how Timothy Dalton got it (personally I don't think he was as bad as everyone seems to think), but then he finally took the role with Goldeneye.

I think he'll at least do another one, if not another 2 or 3.