The next major feature I'd personally like to see added (anecdotal but I've asked around people would love to see this)

Re-work constraints to be more optimized, like physbones.

BUT turn it into a mini-props system you can upload "mini avatars" or something.

And also add in basic bitch system like physbones has to have hand colliders on SOMEONE ELSES avatar to work with

It might require a bit more jury rigging than listed but an in-house constraints that works by default between players to pickup other props (disableable if you want of course) could be small amount of work (i genuinely dont know how comprehensive itd be) and marketed as an entire prop system