I think Tyler Hoechlin is actually a decent TV Superman but you could probably not transpose that to a movie.
They will find someone. Remember that Brandon Routh once upon a time also came out of nowhere.
In any case, James Gunn seems interested in doing a Superman Year One type story, so the actor will be probably be much younger than Cavill.
I wonder if they might have considered Noah Centineo had he not already been in Black Adam.