The thing is that if the DAO is not very successful or for some reason doesn't work very well (can't agree on investments or doesn't get suitable proposals), it will just kind of dissolve as everyone splits out of it.

While that will be seen as a "failure", it would be hardly epic since people would get most or even all of the funds they put into it in the first place.

I for one think that it is probably too big to be useful at this point, but it could very well split into 50 different DAOs all funding different projects. That may not fulfill the great pie in the sky fantasies that people have of "The DAO", but it would fund a lot of startups, some of which will be successful. What it definitely will be successful at is bringing a lot of startups to the Ethereum ecosystem.