To add some nuance to my earlier comment: I don't really worry about the existence of Kakoune (or $OPEN_SOURCE_SOFTWARE_PROJECT) in a trivial sense; we'll always be able to find a copy somewhere and compile it from source, modify it, etc. That being said, I think one of the advantages of a large/durable ecosystem is that it lets me worry less about problems I don't yet have. I use (neo)vim daily, but there are certainly still lots of ways I can improve my workflow. Inevitably I'll run into something that goes wrong or doesn't work like I want it to, and a larger and more active community makes it more likely that someone else has already figured out how to fix it.
The (relatively small) differences in keybindings are also worth a mention, but I think the vims have a bit of an unfair advantage here; IMO learning vim keybindings is almost unquestionably a good investment because you'll find them everywhere.
> Kakoune just feels better integrated with the environment
Out of curiosity, is this an argument for enjoyment or productivity? :) (Either is a fine answer! I frankly can't measure the latter so my personal usage of vim is probably motivated by the former.)