Well, Erlang has been around for 30 years already.
But in Erlang/Elixir you’ll end up writing almost everything from scratch. There were efforts and ideas about it but let’s be real: without real funding and somebody’s livelihood depending on coding that, nothing will happen. We all have jobs to do and families to support. And free time to enjoy.
Outside of that, either Solidus (Ruby isn’t a very good idea for the scale you’re looking for) or Java – although scale might be a problem there as well.
I’d naively pick Elixir and work my way through the difficulties, asking first if I’ll get guaranteed 3 years of funding first. Erlang/Elixir are technologically best equipped for the scale and longevity you’re looking for. But again, it’ll be a custom-tailored and hand-crafted solution.
