Cowan is one of those players who looks like he might have something about him, has huge raps on him from some people in high places (Steve Waugh/Greg Matthews) and he has already played a couple of excellent innings at FC/list A level (particularly the hundred he made at Canberra, t'was very classy). But so far he's been woefully inconsistent, still only 25 so time is on his side, its just a matter of whether he can make the step up and really dominate at state level before its too late (ie he turns 31/32).
David Hussey is probably closer to an Australian cap than alot of people realise, particularly in the one day game, he's probably either 3rd, 4th or 5th cab off the rank atm for a test middle order spot if someone gets injured, behind Hodge and Watson and competing with Katich and Voges, it will just depend on luck, all he can do is keep churning out the runs and hope things go his way. Was somewhat suprised he was overlooked for Voges when Martyn retired actually, as in my estimation they both do exactly the same thing only Hussey does it better, both big-hitting middle order bats and useful spinners.
With Henriques its too early to say as he's still learning his craft, clearly has all the talent in the world as his junior record and peoples opinions of him suggest, but he'll need to string together a full season of FC cricket to give us a better idea. Last summer he seemed to have made the jump up to FC level very quickly with his 5/fer against Queensland, but before you knew it he'd disapeared for the remainder of the season...I'd be suprised/disapointed if he didnt play at some stage.
Rogers, if he scores well at the start of the Aussie summer then he gives himself every chance, if he continues to score as he has done this English season he'll never get close.