If term limits did not exist (and they shouldn't), Bill Clinton right now would be on the cusp of being elected for the 6th time.
2000 vs. Bush...easy win. Not sure who they would've propped up in 2004, but if it's McCain in 2008 Clinton would've destroyed him as well.
Well, without term limits, then a lot would have changed prior to Clinton. I think Eisenhower would have run and won again in 1960. Kennedy maybe gets elected in 1964, but if not then America loses Clinton's inspirational figure. Nixon never gets elected without Johnson, which never leads to a reformist against corruption in Carter, whose struggles never invoke the conservative rebirth of Reagan. New Deal Democrats likely continue into the 1990s and Clinton doesn't really get to the top of the pecking order in that scenario.