For the DAO to fund any projects the ether they took in needs to be converted to fiat. I read somewhere that one of the projects they were considering supporting was a car sharing business in France. You can't buy vehicles with ether and even if you could it would be instantly exchanged for fiat.
Basically the DAO has been used to drive up the price of ether and as they spend those ether to support projects it will drive the price back down. Once the ball starts rolling people holding ether will sell as well.
The idea that the DAO ether are locked off the market is incorrect. Those ether must be sold to make investments. If the DAO does not sell it's ether to invest, the DAO will have failed as an investment method. The only locked funds are those of the individual investors who currently can't get out.
That's not entirely correct some ether will be turned into fiat but a lot of projects will actually be using more ether. Slock.it for example will take payments in ether and part of that ether will be going straight back to the DAO. Most of the early projects will likely have to be like this (due to the undetermined legal status of the DAO).
There is strong support for early projects to be those that grow the ethereum ecosystem for the mutual benefit of ether and DAO users (e.g. ether apps, exchanges like etherex etc.). This will potentially lead to progressively more and more utility for ether resulting in greater and greater buy support. It probably won't happen over night but as time goes on and ethereum use cases continue to increase then there will be continued upward pressure on price for ether.
There is no guarantee but these things are always risky. It was the same in the early days of bitcoin. Nobody ever thought there would be enough buyers to support a price of a dollar, let alone hundreds of dollars.
The momentum behind ether is now getting to the same kind of stage it was in about 2012/13 with Bitcoin so there is very big potential for growth there.
If the Ethereum is used as a fuel for the smart contract system as well as a currency to pay for service, it is valuable.