1 year is not happening. It just won't. I belive when they say they want faster expansions, I do. But a year would mean at minimun Beta would have to start in November along with it's annoucement (I belive they will annouce the expansion but not beta). That is just not happening sorry.
So honestly I don't understand why Chilton even mentioned the idea, though probably it will stay just that, an idea. Because at most I could see this expansion lasting 18 months, that seems much more realistic and feasible to the team. I also belive 6.2 won't be the last patch, but maybe the last Raid.