Add remote.<name>.annex-speculate-can-get config setting for non-special remotes, with the meaning "speculate that the remote knows how to get the key". It's like remote.<name>.annex-speculate-present, except you'd first try git-annex-get in the remote before looking in its annex.

Then one can make a quick clone of the current repo, and instead of re-configuring all its remotes in the new clone, just configure the origin to be a speculate-can-get remote. This would also be useful when you have unconnected but related repos, and want to occasionally share files between them without merging their histories.