> They're already getting to the point of being two different editors with a common lineage and legacy support for Vimscript.

Let's see how much traction Vimscript9 will get. From the distant view of an outsider I got strong NIH vibes from that.

> it would probably have to be Vim basically winding down development. Doesn't seem likely.

It depends on how much Bram was the main focus point of development and if the remaining contributors are able to transition to a less centric development structure.

I would rather expect a EGCS/GCC "merger" than a true code merger. But only time will tell.