Sure, but frankly it's historically very hard to build a business around a specialized database, especially if you have competitors that are even 80% as good bu

Sure, but frankly it's historically very hard to build a business around a specialized database, especially if you have competitors that are even 80% as good but free. The cases where I've seen this work are when the DB offers something way ahead of what their competitors offer. For example, KDB+ was historically unrivaled when it came to ultra high performance time series storage and Aerospike is very hard to beat for extremely high performance multi-node K/V. Otherwise there's little to stop a larger company from offering the OSS competitor to your DB as a service for a lower cost and invest eng resources to close the gap.