I like the rule change possibility - primarily because there would be plenty of guidelines put in that allow a starter to be pulled earlier that fall right in line with typical reasoning for a manager to yank him in today's game.
Throw 100 pitches before a full 6IP, get him out if you want
give up 4+ ER before 6IP, he can get yanked whenever
Obvious one, but if he suffers an injury, he's out.
There's already 26 guys on the roster - teams can use that extra spot for an extra starter instead of one more reliever that throws 98+ who can't go more than 4 batters per appearance.
And it's not about shoehorning the current crop of pitchers who have largely been told their entire careers to throw as hard as they can, as long as possible. If things are allowed to continue, MLB pitcher contracts as a whole will in a way devolve to that of the current pecking order of NFL running backs - teams will bring in a ton of them, ride them hard until they break, then move on to the next flamethrower without having to commit crazy longterm guaranteed money to anyone.