Anson Seibert is ranked the #86 pro prospect by MLB.com. Worth noting that he will be draft-eligible after his sophomore year due to his age, so that may play a role in his decision, as well.
Tegan Kuhns is ranked the #95 pro prospect by MLB.com.
Ty Southisene is ranked the #110 pro prospect by MLB.com.
Jay Abernathy is ranked the #122 pro prospect by MLB.com.
Manny Marin is ranked the #149 pro prospect by MLB.com. Worth noting that he will be draft-eligible after his sophomore year due to his age, so that may play a role in his decision, as well.
Trey Snyder is ranked the #154 pro prospect by MLB.com.
These are the guys in MLB.com's top-200 list published on May 30th. I'd consider any of those a threat to go pro. The price you pay for landing the best of the best, I guess. I might have missed one, but this is a list of guys I'd watch for.