@jefvanbockryck yes this is possible at the protocol level. The Blockstack Core node already knows how to deal with “transfer” requests (and we have lots of tests to make sure it works).
However, the current tooling does not support it yet. In particular, both the subdomain registrar needs to be updated to accept a “transfer” request, and the Blockstack Browser and Blockstack CLI need to be updated to support generating and submitting the “transfer” request.
EDIT: I opened issues for these tasks here and here