Some options I'm aware of:
- FairCamp, by @freebliss - A static site generator to self-host your music and help people pay you for it: https://simonrepp.com/faircamp/
- Bandwagon, by @benpate - A work-in-progress federated music network, with music sales as a planned feature: https://github.com/EmissarySocial/bandwagon
- @mirlo which is a worker co-op
None directly replace Bandcamp, which depended partly on the size of its community and labor from e.g. music writers. But they could be parts of a better music world.