What I would love to see is a declarative object oriented language. It would marry the idea of FauxO from Gary Bernhardt's Boundaries talk [1] with the syntax of Elm.

Elm already allows for escaping into other languages. I would love to see that mechanism expanded and a bunch of "core" DSLs implemented using ideas from the "STEPS Toward the Reinvention of Programming" [2].

[1] https://www.destroyallsoftware.com/talks/boundaries [2] http://www.vpri.org/pdf/tr2012001_steps.pdf