The licensing model behind database drivers is often misunderstood 
Once people see GPL they freak out lol. If you use it like described, you’ll be completely fine. Besides, if you’re gonna use mysql for your games db backend, you REALLY should look at MariaDB. You won’t even look back at MySql ever again lol.
As for the plugin idea, yes please x 2! I HATE wrapping connectors from native code, its a royal pain in the *** and would love a plugin that has it all done nicely for me. Would definitely pay for that sweet goodness.
In response to CriErr: Those claims are just plain ridiculous. Just consider Blueprints as another form of managed code in a sense. I can assure you db access in managed code such as c# is blazing fast. Blueprints will surely tack on a bit more over-head but not enough to be of concern. The real tricky part would be a nice blueprint api, but even just parameterized query support for the blueprint-supported integrals, string types and blobs would be fine for a solid start.
You build it, I’ll buy it! lol