I've done this multiple times now, it's nothing impossible.However, if your application isn't architected to support multi-threading, it can be a pain to refactor all of your code to be thread-safe. In addition, debugging becomes significantly harder when you're dealing with threads and their interactions.
I agree, not an unsurmountable problem at all, just one that may take some time. I don't know how Schine racks and stacks their development tasks - they may prefer to get more alpha features in for testing than optimize servers for better high-player count performance. It would be nice to hear from Schine if this is anywhere in their pipeline, though. Not sure who would be in a position to respond to this. schema, of course. Calbiri perhaps?I've done this multiple times now, it's nothing impossible.
We have also seen that schema is able to refactor the code and replace big parts with new algorithms. (Universe Update/ Turret-Rail Update)
Only make sure the database is not the next bottleneck. Passing entities between the threads should also be not that problem, especially not in comparison to the already existing glitches when passing sectors.
When multi threaded sectors are done, the collision detection could be outsourced to the client if only one player is in a sector. (I know, exploitable by cheaters but random plausibility check can face this problem)