I think the OP is an interesting one. Obviously, the O's are a much better team with Burnes on it, but for the sake of the experiment, if they did sell him at the deadline, he'd easily get a massive package in return. He's set to make 10-12 more starts in the regular season, they could probably weather that storm and sneak into the playoffs, but that is where he'd really be missed.
Burnes would make any true contender probably the odds on favorite, imagine him in the Phillies rotation. Not going to happen, but it's a nice thought experiment.