No. There is a question on how to get machine to cleanly change which machine Docker talks to. The current answer is: standard dynamic config system in docker core, which machine plugs into to change values.
Pluggable scheduling and placement is a good move. It all looks like a straightforward operations research problem ... until you discover that you built a SPOF subject to the network fallacies.
The `-m` flag was already present in docker run. Swarm makes use of that flag to decide on which host to put a container. The `constraint:` setting is indeed new, but (afaik) the values behind it are not pre-defined, so if someone develops an alternative clustering-backend they should be able to make use of that for their needs.
In any case, Swarm will be pluggable, so other back ends are possible and can be developed by other parties.