You can use git or path deps if you want; or set up your own registry (there is code for it, but I don't think it's easy to set up yet. IIRC it's planned, thoughts welcome!)

> Project owners update projects and don't bump the version.

You cannot update code in a crates.io dep without bumping the version. And new versions only get pulled in when you do a `cargo update` or you update a package which bumps the version number of its dependency.