The Seattle Times sounds the alarm:

Few neighborhoods are being transformed more than Ballard by the apartment-development boom that is exploding across Seattle. And few neighborhoods, say industry analysts, are more likely to get overbuilt. About 1,200 market-rate apartments are under construction in this old Scandinavian enclave, now probably better known for its nightlife than for its Norwegians.

Developers overbuild, they create gluts, and then prices drop. Like the developer says:

It's already 50 percent leased, says Billy Pettit, vice president of investments. And rents so far are averaging nearly $2,000 a month, more than Pillar had projected. But Pettit says he has no illusions about the future. "The data just don't lie," he says. "Eventually, we're going to see increasing vacancies, increasing concessions, decreasing rents."

Overbuilding is one way developers—evil, rotten, no-good, very-bad developers—help create more affordable housing. ("More affordable housing" isn't quite the same thing as "affordable housing." It takes a little time, and they do it by accident, but overbuilding isn't something we should worry about too much. Fight to preserve a neighborhood's character, don't let developers do anything (or tear down anything) they want, but let the motherfuckers overbuild.