There's all sorts of groovy hardware that could do the job. Realistically, though, the military is cutting the number and types of aircraft out there, not adding them. That means a combination of R/W coverage in the objective for short-range missions and F/W coverage for longer-range stuff.
I wish we could've put off the Y/Z buy a few years so that we could take advantage of the high-speed rotorcraft developments taking place, e.g. X-49 Speedhawk, Sikorsky X-2, and Eurocopter X-3, but that "train has already sailed," so to speak.
And just so it's clear, if someone posts about the A-10 here, I'm going to bust a cap in their ass.