All 3 were already gentrified in the timelines you gave. Fishtown 2007, yeah I almost bought there. Fairmount 2002 was definitely fine, and Manayunk 1992 was yuppie-fying already. None were nearly dangerous. Is AC hopeless, no I don't think so. But it needs A LOT. Mostly, attract WFH employees, improve the schools, and create jobs for the locals. It all sorta ties together, but requires time & investment. Also a little help from mother nature by no major flooding in the next decade or two.

In fairness, as sketchy as the boardwalk can get, I don't think there's been any gunpoint robberies, which I can't say the same for Center City and Philly as a hole, so there's hope!