Ross and Rachel would not have stayed together
I know the entire series is a will they-won't they about Ross and Rachel — ending with a "they did" — but there is no way the two of them would have remained together.
The only reason they got together in the first place is because, for Ross, Rachel was a nostalgic crush that he needed to prove he could be with, and, for Rachel, Ross was a guy who worshipped her during a time when her confidence was lowest. Both characters grew WAY too much emotionally during the tenure of the show to be in that same place, and I don't see how you get past the "we were on a break" fight. That would haunt a relationship for life.
I think the only reason they got back together was because of Emma, and that's not quite the healthiest reason to be together.
But, prove me wrong: tell me why Ross and Rachel would still be together. And, while we're at it, how are Monica and Chandler doing? (And will Phoebe have finally found David?)