I dont see a problem if you have a half decent case. most mid range cases come with 5+ 120mm fans which is more then enough. This card is as much as a high end gaming rig itself it would mean that most rigs this card goes into will be very high end which excellent cooling.
Agreed, my chassis alone has 9 x 120mm and 6 x 140mm fans (excluding other fans) so this card blowing a portion of the heat into the chassis is a none issue for me.
To bad the card will likely cost a fortune compared to just buying two 5870s.