If Earth really has improved so much after the Vulcans made First Contact, and taking into account that surely there were some serious medical advances given the Eugenics and Augments stuff ... I agree with the average Human life-span moving into the 120's by the 2100's.
As for Trip, I could see him going beyond the average both naturally or through some other means, be it Vulcan life-style and influences or the sort of thing that the novels did.
In the ENT Twitterfiction last September our group had Archer, Reed and Tucker all spending some time hiding from bounty hunters on a planet in the Briar Patch. The BP was mentioned in ENT in
The Augments but it was also mentioned as the home of the Ba'ku in Star Trek: Insurrection (
http://memory-alpha.org/wiki/Ba%27ku). (For those who don't remember, that centered around a radiation that causes the aging process to decelerate.) Phlox couldn't explain the odd readings he got from the three of them when they returned to Enterprise and that's going to be our reason why Trip can live a long life with T'Pol and Archer lives into the AU Kirk's time.