Yeah, we don’t have such worries!
From Monty (MySQL original author) blog:
As I already blogged before, a fork is not enough to keep MySQL alive for all future, if Oracle, as the copyright holder of MySQL, would at any point decide that they should kill MySQL or make parts of MySQL closed source.
Firebird is trully *open* (in all aspects). Nobody owns Firebird, nobody can buy it, nobody can close its sources, nobody can charge for it! So, if you are using Firebird, you don’t need to have such worries.