ScyllaDB is definitely on the radar. The main reason I picked Cassandra on the prototyping stage was because default Cassandra configuration gave me much better performance then ScyllaDB (I know, it is supposed to be vice versa). Another obvious reason was Cassandra's maturity and community support. If gocqlx is indeed a drop-in replacement for gocql, I can't see problems having a separate config/fork using ScyllaDB along with Cassandra.