I think the climate change argument might work for a FIFA permission to relax some rules. Allowing a subbed off player to come back later in the game for the same subbed in player (let's say once only, per player) might be a good approach that adds to the interest in the game rather than diminish it. If necessary allow more than three subs, and have a bigger bench for the game day.
That then becomes an internal change for the game, rather than something that requires working around the broadcasters or other codes which a return to winter league would require. It can be argued that it would take less time to implement than it would be to renegotiate the broadcasting deals that the shift back to winter would entail.