3700 Lancaster will be next. They're in the process of selecting a new developer as Southern Land Company backed out of the development to focus on 1911 Walnut. After that, they will then focus on One uCity Square. The two buildings that will sit between 36th and 37th Streets will actually be developed by Drexel, not the Science Center and Wexford. These buildings will include an Elementary School, and a high-rise mixed-use building.
The full site breakdown is here, and lays out who will develop what properties:
http://ucitysquare.com/wp-content/th.../site-plan.pdf