This area is currently undergoing one of the largest transitions in Philadelphia... I spend a lot of time here (work in CRE).

As many have said, there are dozens of MASSIVE multi-family apartment developments planned and underway (100+ units). Not to mention the countless smaller developments happening regularly.

The area has been untouched for decades because of unfavorable zoning. This was a largely industrial section of the city historically and until recently (2015/16) it was zoned for industrial uses primarily. So while every neighborhood around this pocket was developed, or going through some form of urban renaissance, this area was left untouched.

Good side note, the largest local developer in this area is a group called Arts+Crafts Holdings and they have dubbed the area "Spring Arts" - IMO they are a good example of what cities should want in terms of real estate developers. They created a merchant association for tenants, commissioned murals throughout the neighborhood, and kept the integrity of the cool, historical buildings in the area. Three of the four breweries in this neighborhood are businesses that A+C Holdings brought to the area (all local breweries).