If story progression works the way it's supposed to, as the original townies die off, new townies should move in and take their place. The key word being: should.
I'll agree that Bridgeport isn't very family oriented. But how is the town supposed to get repopulated? There were two male sims and two female sims living in Art Central, but instead of pairing up and having kids like you'd think they would (or even adopting kids), 3 out of 4 of them have died of old age without having children. I've also seen single townies move in, grow old and die...apparently without even having a romantic interest. Elvira Slayer has outlived two live-in boyfriends, and hasn't even had a child. She's an elder now, so those days are behind her. Beau Merrick and Bianca Rubble have been married almost since the beginning of the game I started there, and no kids. And this game has been going for more than 100 days on normal speed. Sims just aren't reproducing at all.
I find that quite odd.