What about Sully, he is not on the list. His rehabilitation after surgery not good enough?
Do proven NBA players even play in the summer league? Except maybe them eternal free agents?
Larry Bird said he was going to play in the summer league if we drafted Len Bias. He was that excited about us possibly getting Len

I suppose it does give players the opportunity to gel and bond. Damian Lillard seems to think so.
As for a prediction, here's an optimist's take.
Olynyk will turn a few heads, like Sully, with his NBA readiness. Perhaps Colton Iverson would too being a skilled big big.
Fab Melo's improvement will surprise many. (Remember I'm being optimistic).
I don't like the shot jackingness of the guards in these games but as mentioned we shouldn't sleep on them. Nolan Smith and Pressey I'm thinking (/hoping) will prove enough to get on the roster and contribute.
Very excited for the rebuild and the SL.