Hack 'n slash is now mostly used as a derogatory term for action games where one can mindlessly click through hordes of enemies withotu any strategy or tactics.
This is nonsense. Hack 'n slash games like Blade of Darkness, Demon's Souls, Ninja Gaiden, Devil May Cry, God of War and even Bayonetta require plenty of tactics and different strategies to beat different types of enemies, which is ironally unlike DA:O where one suffesful tactic wins the entire game.
It is untrue, anyway, that DA2 is going to become a full-fledged fantasy action game. Jade Empire already proved that BioWare cannot do action combat right.. even Mass Effect 2 combat is largely just Gears of War with nicer bricks to hide behind. Going down teh action route in earnest would be just shooting themselves in the foot. BioWare knows what they do best (notice how on the BSN Jade Empire has already been dumped in the "legacy" section) and will keep doing what they do best.