Deal with (name . email) --> (:name "boo" :email "boo@example.com") Add support for the new "changed" field.
Rename mu4e-proc.el into mu4e-server.el Rename mu4e~proc... into mu4e--server... Update users, too.
Usurp more of the utils code than can be re-used without further dependencies in helpers. Split off specific parts in their own file. After the helper/utils changes, update the rest of mu4e to take the changes into account.