[zzzcpan]

You will be able to at least maintain it, fix bugs, security issues. Maybe even start working on new features, promote your fork, revive some of the community, find people with relevant expertise, etc.

Databases are so lock-iny and critical that it's only natural for closed source database startups to be considered too risky to touch.

[manigandham]

Possible doesn't mean realistic. As stated, 99.99% of companies are not going to come close to understanding, forking, and running their own build of a database.

It's better to practice proper vendor management and weigh all the risks and realities instead. If you're not more capitalized and viable then your vendor, then you have more important things to worry about then your vendor disappearing overnight.