People were saying similar things about the post-Watergate Republican Party, circa 1976. How quickly things changed. Never underestimate your opposition!
True. But look at the political parties that have in fact disappeared: Federalists, Whigs, Know-Nothings, Populists. Two of these were national leaders that elected presidents. So I think that the likelihood of them disappearing is at least as high as them remaining. Besides, we recovered because we are right!