If unilateral termination of the player contract is not legal (there are clauses in US player and manager contracts that allow for termination under vague “interest of the club” grounds) under UK law or FA regulations, and assuming no club comes in for him, the clear path forward for ETH is to not include Ronaldo in future matchday squads and no inclusion of Ronaldo in training sessions, not even the U23 squad.
I realize we’re talking about £30 million going up in smoke, but if we can’t terminate his contract then we certainly can’t reward Ronaldo by buying out his contract and then letting him to another club in January.