AO is way too slow for Raonic, his serve will be considerably less effective so I can't see him getting through a decent grinder with an average return and reasonably strong mentality.
Tomic may fail under pressure but realistically he may avail himself of a good draw and reach R16/QF.
Except from those two, I don't expect any other youngster to make some mess in this tournament.
Faster surfaces don't always suit these kind of players, big servers often have poor movement and need a lot of time to hit their rally shots. If he hits his serve the right way, it's going to be an ace most of the times anyway, no matter how fast the surface is (if they're both hardcourts, just looking at that).
On a faster hardcourt however, he has less time to set his groundstrokes up, so I think the AO suits him better than say, the US Open. Because his serve is still a huge weapon, but he's not a complete non-factor once the rally gets started.