Groupon can always lower their cut in the future though once they have built out their database of customers. It also wouldn't surprise me if they laid off half their workforce once their rate of customer acquisition starts leveling off.
To do that, wouldn't they have to admit that they aren't growing like nuts anymore, and wouldn't that kill their valuation? (Even established companies like Apple and Google base most of their valuations on the premise of future growth. When the premise of future growth goes away, you have Microsoft.)
It shouldn't negatively affect their valuation. They would still be able to grow at the same rate, but they would do it by widening the channel rather than by acquiring new customers. It would actually be a big win for investors.
My point is that it if the answer to the 2nd question is "no" for most merchants it doesn't matter how much you widen the channel the business is still unsustainable in the long-term. Even so, how do you see them widening the channel? Going into a completely different model that does not fit their brand? The entire discount space in every market is now chock full of competitors doing similar things to Groupon.
