I guess but I don't really know. Lots of people have Cassandra in production. I suppose there is a certain segment of that market that needs a super high performance version, but is it really that big?
Cassandra is supposed to be a high-performance database, except it has some fundamental issues that keep it from being what it can be. ScyllaDB fixes those fundamental issues so anyone using cassandra can benefit from using scylla instead.
For many users, that "super high performance" really just means lower request processing latency, which is a very desirable feature to have in various market segments. Look at the various benchmarks available (or run the benchmarks yourself) and you will see that Scylla has a very consistent, low latency that's a direct result of its non-blocking, shared-nothing architecture and implementation in a non-manage language, which gives us more control.