Even though vehicle combat has gotten fairly mixed reviews, we know for a fact that it works rather well in PvP implementations such as Lake Wintergrasp and Strand of the Ancients. Wintergrasp, in particular, has been so popular that it has created all sorts of problems for Blizzard, leading to the development team finding ways to actually reduce the number of people playing in it. If Wintergrasp is any indication, the Isle of Conquest should be incredibly fun, as well. The key word here is "large-scale", which hopefully indicates a return to Alterac Valley-level epic battles.
It's too soon (and rather pointless) to speculate on the mechanics of the Battleground, but it leans towards being of bigger scale than the fifteen-man Eye of the Storm or Arathi Basin. I mean, you wouldn't call either Battleground "large-scale", would you? At any rate, with all the data Blizzard has gathered from the success and popularity of Wintergrasp, expect Isle of Conquest to be several steps in the right direction.
In other news, it truly looks as if we should get used to shorter Arena seasons, with Season 6 seemingly coming to a close with Patch 3.2. The biggest question here, however, is what PvE gear will the new Arena and Honor items be matched with? The answer might lie in the same patch preview -- the Argent Coliseum. With unique 5-man, 10-man, and 25-man challenges, there's bound to be equivalent gear. So even if Patch 3.2 won't contain Icecrown Citadel just yet, there'll be a whole slew of delicious new gear to work for.