Lack of maneuverability would seem to be the weakness in the hypersonic concept. As velocity increases, you're going to need more control surface to turn the thing and that means drag - seems like some contradictory forces at work. Pilots over N Vietnam were shot down by SAMs, but more often they lured the SAM into an intercept and then turned more quickly than the SAM could turn - a lot of times they did run out of speed and airspace to defeat the third or fourth SAM that targeted them. Hypersonic missiles seem to be defeatable given enough warning, but the speed cuts down on warning time. Lack of maneuverability of a hypersonic missile does seem to play into a Patriot's favor somewhat - assuming the Patriot is along the hypersonic missile's flight path and the lock comes early enough.