There are huge opportunities to do this too. At blizzcon, they appear to have organized the archers to back up and attack. They also allow pathing 'priority' (as where the crusader 'pushes' the scarabs), which means that pathing could take a titanic leap forward. I can see the strategic component of the game making a big come-back.
Beyond even this, Blizz has a big oportunity to make some really compelling mechanics changes between D3 and the expo. Currently, A1-5 normal is exactly the same as A1-5 inferno. This can be completely reversed here, with major changes to game mechanics between the different difficulties and different acts. If this isn't done, I would consider it a major failure.
Overall though, I saw nearly nothing deling with what I consider the bland, uninspired battle mechanics. Lore, itemization, and monster graphics appear well in hand, but that isn't enough to make good GAMEPLAY. In essence, if this is just a 'whirl for the win' expo, I can't really say I could be convinced to proceed.