I mean just how much explosive can you fit into a shoe? Really. And Boeing builds very rugged airplanes. They have been doing it since the legendary B-17 of WWII, one of which was tough enough to fly back to base after a mid air collision with a German fighter. The modern 737/777/787 jetliners are very strongly built. I think the best a shoe bomb could do is punch a smallish hole in the skin, depressurizing the cabin. This would be exciting for all on board, but the plane will keep flying.
TSA snoopers must love this. Another excuse to make life miserable for passengers.