What comes after v0221? The original devs are working on "v0222," which promises a "Colossal Titan" boss fight with destructible inner gates. Astronut has teased that they will repack v0222 as a delta patch (only 500 MB) rather than a full download.
For the modding archivists out there, here is the technical breakdown of this specific release: attack on survey corps v0221 astronut repack
Furthermore, rumors suggest an "Astronut Launcher" that will auto-update the repack without re-downloading the entire 9 GB. If true, this could revolutionize how modded fangames are distributed. What comes after v0221