I'd like to quote the Blueprint page;
http://auroracoin.org/blueprint.phpIf more than 6% of the total Airdrop supply (10,500,000) remain in the premine addresses after Stage 3, any coins exceeding the 6% mark will be verifiably destroyed.
50% of the remaining coins will go towards a development fund and/or towards an Auroracoin foundation formed by the community. The other 50% will go towards a charity or charities, to be determined democratically by the Auroracoin community.
The right is reserved to repeat the Airdrop reset stages as many times as necessary to get the coins into circulation, as well as any other measure intended for the same purpose.