It'll be Rasner for now -- with Bruney out, it will be a while till Joba is transitioned into the rotation.
As for Hughes, the popular belief among Yankees fans and media is that he's not actually injured; rather, this is cheap and easy way to get him out of the rotation for a couple weeks so he can cool out and work out the problems he's been having. So if you're dropping Hughes because you're concerned he's injury prone, I'd advise against it -- there's almost no way this is actually an injury. If you're dropping him because he's been ineffective...well, I wish I could say you were wrong, but the numbers don't lie. Still, I think this is a bump in the road, and he'll be back on track soon after he returns.