I haven't yet used one of the recent MySQL forks, but I have a feeling the next time I'm using an OSS solution that requires a MySQL variant, I wont be using MySQL.
Drizzle is not a drop-in replacement for MySQL. The only real option if you want to replace MySQL without having to change your application code is MariaDB. Drizzle is fine for new projects, but you'd have to massively alter an existing site to get it to work with Drizzle.