It is possible to create a (C/C++) project that have source roots on remote file system. Unfortunately version control isn't able to work with such projects. And, which is worse, the versioning frametwork itself (VCSContext, VcsVisibilityQuery, etc) often works in terms of java.io.File, which makes impossible to create a plugin capable of working with remote file objects.
I probably missed two issues that should be separate. Let's assume this one concerns lacking CND functionality. I'll file related one against VCS shortly.
Added to NB 7.0 Release Notes
Workaround: use versioning tools directly on remote host (via ssh, etc.)
The framework was fixed a while ago