I don't think it's an unrealistic hope to hope for Proctor, Mitchell, and Roach to all come back. But if this season is going to be at all a success for us, Proctor is going to have to build on this last three games or so, when he started showing why he was a top recruit. And if he does that then he's probably gone to the NBA.
So it's kind of a double edged sword. Proctor plays well down the stretch, the team does better, but he goes to the NBA. Proctor plays mediocre down the stretch, the team does mediocre, but we might get Proctor back.
I don't think there's anything that Roach could do realistically down the stretch this season to result in him being a likely second round pick. So I don't think he's going anywhere. I know others think he'll transfer. I don't agree (based on nothing more than gut feeling).
And Mitchell is a dog, but I do not think he's showing enough that a team uses a pick on him this year. I'd be very excited to see a year two (and three???) out of Mitchell.