In terms of availability, right now here's what the Canes have:
RHD: Hamilton, Faulk, Pesce, and TVR at the NHL level. McKeown, Fox, Luke Martin (probably furthest away)
LHD: Slavin, de Hann, Fleury at the NHL level. Bean, Carrick
I believe the team will trade Faulk at some point in the next 12 months, but that still leaves Hamilton, Pesce, and TVR at the NHL level along with Fox (if he signs) and McKeown. Therefore, I think McKeown would probably be available, BUT, because he is still waiver exempt, the Canes likely aren't looking to move him for the sake of moving him.
In terms of NHL readiness, hard to say. He looked good last year in his stint in the NHL. Solid but unspectacular. Kind of reminds me of a poor mans Paul Martin in that he does a lot of things well, but really isn't spectacular (or terrible) at anything either. If the Canes didn't have the depth they have and had to use him as a #6/7 this year, I wouldn't mind it at all. That said, sample size is small and for a guy that is "solid but unspectacular", it's sometimes hard to gauge how NHL ready he is on a small sample.