Cloud sync is for On Premise to and from one or more Cloud Networks. It is built around the use-case of working inside and outside a corporate firewall.
On premise to On premise or Tenant to Tenant is a similar but different use-case. While some of cloud sync may be applicable there will be differences. In particular there's far less of a problem/issue with scale since its not a case of thousands of repo's fanning in to one cloud instance.
Looking into the crystal ball there is a need to merge cloud sync, import and export, transfer and multi-tennancy. Its the next iteration of transfer that I think will be for tennant to tennant syncing, not cloud sync.