Issues #9-12 were originally solicited for March, April, May and June with art credit shared between Hitch and Daniel Henriques on #9, #10 and #12 and full art by Neil Edwards on #11.
There was also meant to be an annual in June written by Hitch with art by Edwards and Henriques.
However, the text of the solicits seems to indicate that #10 is the final issue of the big Rao storyline, with #11 an ‘aftermath’ issue, #12 starting a new story arc and the annual being a standalone story.
So I would expect us to get at least #9 and #10, and possibly #11 if Neil Edwards has already got started on the art, to finish off the Rao story before the Rebirth relaunch hits.
Perhaps whatever has been written for #12 (and the annual?) will instead feed into the relaunched version of the book.
(That was a very long-winded way of saying “not sure”. )
With Hitch presumably off art post-Rebirth, I think he could still carry on as writer for quite a while. He said when he first started the book that he had lots of stories planned, and that his overarching vision for the book relied on some quite long-term plotting.