At the end of the day you'll have to trust the framework to do the right thing. We take care of the edge cases for you.
But this doesn't tally with this:
SpaceBase only supports spatial queries. Future products will be built for other kinds of queries as well.
If you see online games as spatial simulations then they are a suitable nail for your spatial database to hammer. But that is one particular reductionist view of games. Much of the game has little or nothing to do with space and doesn't benefit from spatial coherence. Solving the spatial problem well is hard, which you know, and which is why you feel that what you've made has potential worth. But game developers realised that the spatial problem was hard about 10 years ago and designed around it, in a way that suits the rest of their game and which isn't limiting when faced with non-spatial queries. Unfortunately you're now coming along with a solution to a problem most MMO developers don't really believe they have, and asking them to change everything about how they work in order to take advantage of it. As mentioned above, this is 'high friction'.
Auction houses, global chat, guilds, private messages to anybody in the world, a Who list, etc. - these are the real "edge cases" in your system and you don't seem to be giving positive responses to how they would be handled. If SpaceBase does not let me implement them, or forces me to have a parallel database that I must maintain separately, then it is not suitable for MMOs. This is something you'll have to think hard about.
Project Darkstar was shutdown before reaching the point of a multi-node distribution.
The 'project' was shut down, in terms of funding being withdrawn, but that doesn't mean so much for open-source. The people who worked on it had multi-node up and running, and the contention costs were so high that adding nodes actually reduced performance, hence it wasn't distributed in that state. It turns out that an optimistic locking model degrades significantly when distributed across the network and when the simulation's spatial coherence is not high enough to keep interacting entities colocated, with a resultant cascade effect when entities end up spending more and more of their time on the wire and not in memory.
For some reason, when you show a new technology to someone at, say, Twitter, they'll immediately start thinking how they can take advantage of it.
Startup tech companies have almost literally money to burn in the name of research and discovering cool things. Twitter has been run almost entirely on the back of investors throwing money at it in the hope that they find a way to turn a profit later. Not only can they afford to experiment, but arguably they are being paid to do exactly that.
Games companies are not tech startups. They are rarely funded by investors in the same sense and are much more linked to retail sales. There's little room for experimentation or risk-taking. Making games takes a lot of time, and most projects are not profitable anyway. As a result, you almost always need to reuse the code you have already invested in. It doesn't make good business sense to throw out half a decade of past work to take a chance on a new language and indeed a new paradigm for your next game when you have firm market evidence showing that customers are happy to play in the type of system that was designed several years earlier. This may seem conservative when compared to the world of websites that make a loss year after year, but the market conditions for these businesses are very different.