It's clear that there will be a successor to Git some day, in the sense that Git is a successor to SVN (yes, I know Linus's viewpoints on SVN). But the successor won't be a "better Git" just like Git isn't a "better SVN".

The driving features of Git's successor will be unrelated to Git UI gripes. If Git's UI gripes were important enough, people would just be using Mercurial (which has it's own quirks). The biggest problems I've personally seen with Git are the same problems you see with other VCS, where two people change the same file, and one commits the changes first. Now you have to merge the changes and sometimes it's a pain in the ass when you just want to submit your changes and go home. A better VCS isn't going to solve that!

I'm still glad that Git delivered me from all the merging problems that SVN had, although I've heard that SVN is a little better these days.