I wish them well but fear this won't work out for them. This sounds like a smart move until you realize that they are just one of many players in a crowded market and that this actually decreases their value proposition for end users and external contributors. Having less of both is bad news for an OSS project, no matter how you spin it.
The way I see it this type of company has a short term value that derives from them being first (more or less) to market with whatever it is they do well. In this case, their thing is having a sharded/clustered db that can replicate across datacenters and with serialized transactions.
Awesome, that's a great thing to have and it will take other databases a while to get there. But they will eventually and that matters. This stuff commoditizes quite rapidly. It's based on published research by Google half a decade ago and people can look at the source code and algorithms. It's just a matter of time before somebody else figures out how to replicate what they do in some other product. Somebody like e.g. the postgresql developers: https://tapoueh.org/blog/2018/07/postgresql-concurrency-isol... and https://pgdash.io/blog/postgres-11-sharding.html. It's probably not perfect yet but they are obviously heading the same direction and there's a notion of good enough and diminishing returns.
When it does catch up, it all reverts to which is the best product in the market. Part of that is features but another part of that is a robust developer community and having access to robust support and hosting options from multiple companies. A failing VC backed company that controls the code base and treats it like a walled garden means that community is only as good as that single company behind it, i.e. not very good. It simultaneously repels potential users and contributors thus slowing down adoption and development speed while increasing the R&D burden for the single backing company to not fall behind any further. They can't win that game.
In a nutshell, postgresql does not have that problem and it never will. Mysql doesn't have that problem either. Both developer ecosystems consist of collaborating frenemies that work together because it is better than not doing so. Both provide pretty good database solutions with plenty of hosted solutions (including Amazon and other cloud providers), commercial support via several companies, etc. Also both are pretty much guaranteed to continue to have active development for as long as there are people willing to sell their time doing that and there are so many companies using both that there is just no way that that would change within the next few decades or most likely this century. Essentially all of the current companies behind both could go bankrupt and all that would do is create an opportunity for new companies to step in and take over.