I will say that something that hasn't been done is to draw up the distinctions between "must work" and "wacky cool thing that @hostilefork likes but doesn't matter to others".
e.g. to my mind, invisibility is critical. Once I had it, I didn't see how a Rebol-like language could live without it. But how much simpler would things be if it didn't exist?
With the help of AI maybe each of these features can be "costed" and seen how much you wind up paying for them, and get some metrics of what kind of scenarios make it "worth it" and why...vs. just my intuition.