We’ve looked into threshold crypto a little but so far haven’t been able to find a system that suits our needs. One complication is that the shared keys need to be constantly regenerated as new nodes are added and removed, and sections merge and split. Creating a system that is decentralised enough and fast enough for this kind of use seems like a really huge task (if it’s possible at all). That said, if we did find an appropriate system it would definitely be considered for adoption.
(that’s my take on it anyway from the last time I looked into it)