Oracle bought the rights to InnoDB, MySQL's best backend, some years ago, and they didn't kill MySQL with that.

Both MySQL and InnoDB are GPL2 licensed. The worst thing that could happen is that Oracle stops developing them, but there's nothing preventing it being picked up by someone else.

Okay, the worst thing is that Oracle starts enforcing patents against the (users of the) products, assuming they have any that are valid and relevant.