There hasn't been a word about it, Yazawa has been fine, it seems... and apparently she has a twitter account, but I can't say it's real or not. Even if it was real (that, would be the case) she does not talk about NANA in it. Or so I was told about.
I don't remember exactly, but last year Yazawa did something aside NANA that was a song for a singer... and I think there were talks that Yazawa seems to have drawn a Christmas pic for the past November/December... but I don't remember the details about it. Even if Yazawa is alright (it has been almost 2 years since she got off from the hospital), the thing is depending so much on Shueisha and Ribon/Cookie.
And who, knows, maybe she is finishing the manga by the time they decide to publish it. There hasn't been so much to tell and it was already in the final 'arc'... so maybe she is already finishing details in case she gets sick again? It's pure speculating since no one knows about it.