I could imagine it in a generation or two, maybe, but for any mainstream political movement in the next 5-10 years, I'd bet you're right. It's way easier to tell people that the warm fuzzy feelings they have about "American ideals" are fine, but that we need radical change if we want to actually live by them, than it is to tell people that their country is shit and those ideals are shit and they should feel like shit until they destroy it. I'm also struggling to think of any successful socialist movement that's lacked a patriotic element.