If BlueSky banned you tomorrow what is the plan? If BlueSky went bankrupt tomorrow?
I figure there are other AT compliant products that you can switch to but a lot of data would go missing?
And of course there are several implementations and hosts for relays (the gossip nodes), PDS implementations, clients, and appviews (the server backend for bluesky the web app).
So strictly speaking if bluesky imploded tomorrow you could just use a self hosted version of the same app or use someone else's (such as https://zeppelin.social).
The PLC directory is still technically in bluesky's hands but is being transferred an independent foundation atm and could be trivially forked if needed. And of course if you use did:web that doesn't apply to you and you just depend on DNS.