Discounting The Coupon Companies

Groupon and Living Social have problems. McArdle wonders if they are doomed:

If one of these companies survive, my money's on Living Social; at least from my customer perspective, they've done the best job of pushing into markets that actually have some potential, sustainable revenue.  But it's quite possible that none of them will.  They may just be this generation's, a service that was hugely popular with venture capitalists, and New Yorkers–but only as long as it was selling its product at a loss.