The new WOW exp will be in the old continent Azeroth. They will be rebuilding the land here and there to fit it in to the new story.
Also they will be upping the lvl cap to only 85. Normally its 10 levels. No new classes. I think Blizzard is going for the easy ride with this.
Low effort and max outcome. I'v seen a few of the screens and the new land doesn't look that upgraded to me. Now were near the graphical content upgrade we saw in WOTLK.
Then the level cap 85. Sry but only 5 lvls for a whole expansion. Sure the levels will be harder. But it's not only the difficultly, we also get less new spells, etc.
And then the old bosses, Ragnaros and also Nafarian will return, fun, but ill hope there will be lots of new bosses to.

Personally I was looking forward to a new continent, with all it's new lore.
Ques I have to wait another year orso.

Mel