I looked at this thread, and I thought:
"Please, let this be anything but this hawk transforming shit."
Then I entered this thread... well, you know the rest.
I mean, seriously. The cursed seal is not some divine power, it's a power that has come from some fucked up research made by Oro. And I seriously doubt that this fucked up research will just magically turn into some hawk. The closest the CS is gonna get Sasuke to be a hawk, is with some ugly handwings, also known as CS2. And these wings are just large duckhands, and that's about it. He could fly with em, he could use them for pretty good defense, I mean they had their use, but he won't be growing some feathers anytime soon.
I really don't think that this hawk-snake stuff was meant literally. I think it was more of a comparison. Of course there is always a possibility that Sasuke would get some kind of hawk form, with a jutsu, or with Sharingan, or something like that, but the last thing I would imagine, is that he would get if from CS2. The cursed seal is power made by a crazy snake-man called Orochimaru. If anything, the cursed seal will only turn him into something closer to snake, than hawk (not literally speaking).