As a bit of a veteran in the database industry, I concur (at least about the impact on Oracle's database business). There is a lot of pent-up demand for anything that offers distributed consistency.
We've been seeing this demand at Fauna. FaunaDB offers distributed consistency, based on Raft and the Calvin protocol instead of depending on specific networking and clock hardware. We've seen a big part of our appeal is the ability to run FaunaDB across multiple cloud services.
The serverless cloud is pay-as-you-go. There is no minimum spend, unlike Spanner's $1000 per month (apparently). And it's cheaper than operating any open source on cloud hardware.
On-premises is licensed by core.
We have a developer edition you can use on your local machine, but we don't currently have plans to open source FaunaDB itself.
While I'm not familiar with Spanner's inner workings, I would guess that they recommend 3 instances for quorum establishment in case a region becomes unreachable. If that's the case, using fewer than 3 instances could cause major problems.
Since Spanner currently only supports single-region deployments, it clearly isn't recommended as protection against a region becoming unavailable.
It may be recommended as protection against an availability issue on an instance, though, which is, after all, a big reason why you'd want a distributed DB in production.
I suppose the loss of a region doesn't apply (yet), but yes, the quorum requirement would still apply even if you only had instances in a single region.
We've been seeing this demand at Fauna. FaunaDB offers distributed consistency, based on Raft and the Calvin protocol instead of depending on specific networking and clock hardware. We've seen a big part of our appeal is the ability to run FaunaDB across multiple cloud services.