I hear you. Its impossible to predict when, I agree, but there will be a straw that breaks the camel's back.
As for politicians' abilities, I think you give them too much credit. They didn't engineer the economic enviornment just exploited it. With few exceptions they are just lazy average thinkers who focus their energy on oisher v'chovod, not on any master planning or conspiracy. The fact that America enjoyed an economic boom from late 1970's can be attributed as much to Baby Boomers reaching peak productive years, doubling the workforce by adding women, increased efficiency of the working class, etc- just as much or more so than any policy that politicians can claim responsibility for.
If this is the best they could do with 40 years of boom, what do you think they can accomplish in a stagnant or contracting economy?