Tors with cached consensuses can't upgrade to a version that stops supporting a required protocol
When Tor loads the cached consensus, it checks the protocols in that consensus, and then exits if it does not have any required protocols. These checks happen before signatures and expiry are checked. (And before trying to get a new consensus.)
This makes it impossible for a Tor with a cached consensus to stop supporting a protocol required in that consensus.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information