I'm thinking on how a DAC company make profit. Here is my idea:
If some company tries to make profit, the company should provide something valuable to the others. Then people will pay for such valuable thing.
So what kind of valuable thing can a DAC company provide? What the company provide is depend on what the company has. The real companies like Google, Baidu make huge profit from ad because they have large number of users. A successful DAC company will also have a large number of users. So DAC company can make money in ad market.
Is this attractive enough for a real company to put ad in a DAC company? The answer is positive if DAC company has many users. In view of merchant, they pay money for ad not because Google will buy their product but because Google can send product information to potential consumers.
Ad business is helpful for bitshares to be accepted outside DAC company. If some merchant want to make ad in DAC company, he should pay for this. In real world, USD is currency, BTS is unaccepted, but in DAC company BTS is currency, USD is "unaccepted". So the merchant should buy BTS with USD. This is just like the situation when an American buy something made in China, the American need to change his USD into CNY. We can tell that BTS is accepted by merchant in such ad business.
I think such business plays an important role for a DAC company just like mining because business create value.