I've got to think that if we got Conley and the #2 pick, we'd take Rubio and immediately put him at the backup. Starbury would be gone.
I really can't see the C's taking Rubio. I think if they made that trade, they would then use the #2 pick to get someone to help sure up another position of need, and then get a veteran PG through FA. Or they could turn it into a 3-way deal, where they get another veteran, and trade down a bit.
My guess is they would end up with someone like Harden, Evans, Henderson, or Blair. Someone who could step in immediately and play minutes, but would still have some upside.
Rubio is just too much of a question-mark, and has too many holes in his game right now. Not to mention, trading Rondo, really only makes sense if they are going to be strengthening 2 positions of need, rather than just getting two young PG's.
Now, if they got Gay or Mayo instead of Conley, that would be another story. Then I could see them bring Rubio along behind a veteran PG, with Mayo or Gay solidifying the wing, and taking over for Ray next year...but I don't think Memphis would give either of those guys up along with the #2 for Rondo.