Realistically, I won't be surprised if Sam leaves. But let's put ourselves in his shoes here for a minute:
You come to a school where you are very close with the coach for all four years. He is gone for your final year. You haven't met the new coach, so you're apprehensive. You have a unique situation (because you were a solid student) to go to grad school elsewhere, or at Bradley.
Why on Earth would you just "wait and see" for the new coach before doing ANYTHING? I'd be getting my ducks in a row, opening up options, and then waiting to meet the new coach. If you like him, do a masters here. If you don't? Bounce to one of ten schools who will take care of you there and also allow you to play ball.
No doubt if Les is here that Sammy stays and does a masters here, but that's not the case. Why not get some options, just in case? And doing it early (before the new coach) gets more schools to look at him. Sam is smart and hard-nosed as we have all said... But it's not just on the court. He is a smart personal overall and making sure he has good options.
Good luck on your decision process, Sam -- you deserve a fair shot anywhere!