Yay! Thanks to Lennart people are actually talking about how VCS diversity is a problem.
And Lennart thinks that maybe, instead of the slow drift toward VCS convergence and interoperability that I've been expecting, we might instead reach a point where everyone decides that there can be only one.
I'm reminded of 1993. Using the internet at that time involved using a mishmash of stuff -- Telnet, FTP, Gopher, strange things called Archie and Veronica. Or maybe this CERN "web" thing that Tim Berners-Lee had just invented a few years before, but that mostly was useful to particle physicists.
Then in 1994 a few more people put up web sites, then more and more, and suddenly there was an inflection point. Suddenly we were all browsing the web and all that other stuff seemed much more specialised and marginalised.
You can argue that this was essentially a popularity contest, that Worse Is Better suggests we didn't pick the best solution; that the web/git, at its core, sucks, or that gopher/svn rulez. Heck, I've espoused most of these positions myself.
But the reality of network effects can be very strong, and reality can trump all these ideal-world arguments whether we like it or not.
Previously: The New Portability Nightmare