Package management is a really difficult problem to solve, which linux package managers have barely been able to solve. In addition to this, each programming language usually has its own package manager again, which vary a lot in quality.
Windows already has locally deployed assemblies and central side-by-side (SxS) assemblies that can accommodate multiple versions of the same assembly, complete with major/minor versioning, redirection etc. Windows Installer supports reference counting and automatic uninstalling for the centrally deployed assemblies.
This new OneGet package manager is for solving the availability and automatic updating of packages. But Windows is not going to need separate repositories for each incremental update of Windows and the ABI.
If there are two software packages which depend on different version of a third party package, then the usual practice is that either the third party DLLs are included in the package or both the versions are specifically installed.
I think this is the way that OSX works as well - it is only Linux that works with centralized dependencies, which is what needs a very sophisticated dependency management solution.