Article this morning from Harvard Business Review highlighted possible trouble for the growing social coupon web service. Citing lack of a business model that benefits from "significant network effects" or really any clear long-term business model, Groupon does not have a clear (and positive) future.
I'd argue a huge missing piece from Groupon is the terminating incentive for customers to share a purchased deal. LivingSocial, for example, has a buddy-system for customers: upon purchasing a deal, you get a unique link to share with friends. If (3) friends buy via your link, you could get your deal for free. Incentive to be a marketer for the program sets it apart from Groupon; however Groupon does have a buddy system albeit a non-purchasing-event, they do offer $10 for every person you refer sign up with Groupon.
Despite recent news of IPO offerings, the falling sales and non-existing profits just won't cut it for the start-up. Is this the early stages of the start-up bubble popping or just bad calls on Groupon's part? Can the social coupon sites survive with so many conflicting business and customer opinions around the perceived model?
What social coupon sites do you use? Are there any reason besides timely and interesting offers you pick one site over another?