Sorry I haven’t posted anything on this, but here’s my status update.
I do have some work-in-progress ideas, but to implement them fully, I’ll need SpongePowered/SpongeAPI#1370 to be merged. It’s been put on hold, as SpongeAPI version 6 is going to be for Minecraft 1.11 changes only. All other breaking changes (such as that pull request) will have to wait for API 7. Once it’s merged, I’ll get my ideas finished and implemented.