I watched Matz recent keynote about the future of Ruby. I wonder if Ruby can become an immutable language? That could be expedited by a port of Clojure's immutable types. Then add concurrency and distributed computing (perhaps modeled after Erlang). That surely would be a-ma-zing!
Yet, I am not sure how well OOP can mix with this. But if it can be figured out, I think it would be worth it --more than anything else I can conceive of for a Ruby 3.0. Of course, this is also a HUGE change.