At work we have a VCS that is obviously trying to compete with git while adding in the buckets of functionality people who actually pay for a VCS demand. Its OK, nicer to use than git, but not as powerful either.
I think git-improved is only going to come from the open source space. The vcs we use is bloated enterprise-y nonsense that is packed with bells and whistles and is a resource hog, you're not going to get regular developers interested in it, but you're never going to sell many copies of a vcs without that nonsense so you have to have it to satisfy purchase requirements.
If a git-improved turned up tomorrow and showed everyone how to do it and cost $1, someone would just nick those features and toss them into git proper before git-improved could get any traction.
What git needs is some fresh porcelain. We started with just git plumbing, then got the porcelain, but I think that the porcelain should be rebuilt knowing what we know from years of using git.