Letting the market it handle is a contradiction. We are the market so let's handle it.
Well, we have to agree on a problem first. I think it's too early to know if there is a problem or not?
With deepbit, we know that someone with >50% of the network can harm the network. (And I don't think this problem has been solved yet.)
Here, some think there won't be enough profit from transfer fees to provide motivation to mine. This is just speculation and I don't see how we can fix it.