Vaultwarden will survive. Since the client is open source, once they close the API and break compatibility of the clients with Vaultwarden, the old version of the app can simply be forked and rebranded. I also do hope that the KeyGuard app will continue to support vaultwarden as well since if bitwarden closes the API and makes a breaking change, as is likely to happen, it will break KeyGuard as well, but it will still work with VaultWarden for some time.

The real issue is that many people who are using Bitwarden aren’t savvy enough to host Vaultwarden in a secure way. Many people are careless with things like secret keys and such and dont know how to properly secure a web facing app or a VPN into their local network. But anyone who self hosts should result learn those things anyway. This one just happens to be a particularly high risk since it contains all of your passwords for everything else.