We have a mix of version control solutions and some of our SVN repositories are used by 5000+ developers on a daily basis. Work is done on the trunk and we make weekly release branches.
The revision numbers are approaching 300k.
If we had 100 developers, we'd likely still be at a high number as we check in at the end of every day and automated nightly processes also cause commits. So the revision number is more a function of the age of the repository and commit policy rather than number of users.
Conversely, we have other per-team repositories for different projects and we've managed to get into branch/merge hell with these with only 25 developers. So we're moving those to git.