The key words you used are "most likely" and at least you're honest enough to use them. There is no mathematical proof that any cipher (other than the one-time pad) is resistant to all as-yet-unknown quantum algorithms. That doesn't mean that they are actually vulnerable - only that we cannot know with certainty whether they are.
That's the usual situation in complexity theory and it applies to classical algorithms as well. There is also no proof that quantum computers are actually superior to classical computers when it comes to cryptanalysis. Still, most people believe this to be true.
People seem to under-estimate the NSA's capabilities here when I talk to them. They employ a lot of really smart people, and they have the benefits of reading all the public literature as well as all the classified stuff that their academic peers cannot read.
Remember that we're talking about actual physical devices that need to be built and being really smart only helps you somewhat when you need to solder electronics or align a laser. And so far, the NSA employs hardly any physicists which you can also tell from the fact that they've outsourced the research mentioned in the documents to a public university. This is very different than in mathematics or computer science, where it is well known that the NSA is a large employer. That being said, I still think that the NSA might possess some interesting knowledge on quantum computing. I wouldn't be too surprised if they were sitting on an efficient quantum algorithm breaking AES, for instance.