33 years here, and that's *exactly* where I am. Emacs... is fine. I mean, there are new features occasionally that are worth using. There are new paradigms it would be nice for it to support. But major architectural changes just seem silly. It's *done*. How many pieces of software ever get to say that? How many of those are entering their fifth decade of popular use?
Just leave elisp alone. I see nothing but grief and churn in this direction.
When I hear concurrency, I just hear bugs and complexity. Imagine writing some code trying to adjust a package and dealing with concurrent logic. One of the thing that make emacs so easy to modify is the global state. With concurrency you will have to hide database-level code to deal with that, or replace it with a more complicated mechanism (actor models?).
Just leave elisp alone. I see nothing but grief and churn in this direction.