Here's the timeline:
P&A's last consecutive chapter--Last Summer of Youth--took place the summer of P&A's Junior year.
Then there was a fairly massive skip-forward to the five-year reunion, wherein we learn that P&A stayed together for a little while, then broke up, and pretty much stayed that way, though they remained friends. At the end of that arc, however, there was a hint they might get back together.
Then we did a partial re-wind to the beginning of QUILTBAG--taking place the first year of college.
Now, at this point in time, Sara and Penny, and Lisa and Aggie, are still good friends, so they are probably going to be in touch occasionally. However, this is during the hiatus in P&A's relationship--each of them is off doing different things (and people) at their own schools.
So P&A might make individual cameos (say, when the girls go back home for holiday breaks), but really, T. is done with their story--it's now the Lisa and Sara show.