If a product is 10x better than what's currently available, it will see rapid adoption. There was obviously something about git that made it MUCH better than the precursors and that's why it obliterated everything else.
I highly doubt that new tools will be 10x better than git. Maybe 20%?
One way I compare the git to jj transition (if it happens, or for whom it happens) to the svn to git transition is: branching in svn was awful. It was heavyweight and you were signing up for pain later down the road. Git made branching easy and normal, almost something you barely need to think about. jj does a similar thing for rebasing. For someone whose familiarity with git is clone, pull, push, merge, creating branches (so, basic/working/practical familiarity but even "rebase -i" might be pushing the limits)- for someone like that what jj offers is a similar "lift" of a feature (rebase) from "scary" to "normal" similar to what git did for branching compared to svn.
That's just one aspect of the whole thing, and of course if you're a git rebase wizard (or have tools that make you that) then this won't seem relevant. But I think for a lot of people this might be a salient point.
I'm happy to give it a try when I have some time, but I have 0 problems with git right now so it's not top of my list. My critique is also really not towards jj specifically, I'm just discussing the idea that git has extremely wide adoption now and that this has benefits :)
