Norman Podhoretz, in a long essay, asks and answers the question.

Podhoretz does bring up interesting points. I don't know if the "Bush doctrine" is going to live or not. But it does seem extremely expensive to sustain the current obligations much less cover the rest of the problem areas of the world. Frankly, if someone does get it to scale up, then the doctrine probably should be named after that person.

At least, if the current supporters ever get back into power, they'll remember this taste of humility.

I think part of the reason for the longevity of policy decisions like this is that they are based on the existence of some problem. As long as the problem continues to fester, there will be support for the respective policies that are intended to address the problem. Especially if the policy turns out to have a positive impact.