? I do wonder if we'll see them in the near future though.
Been thinking about this for a while and I think I finally get it. There isn't really a point for manned hypersonics, if you pull any maneuver at mach 10 you'll be vaporised, plus you'll never go faster than a modern missile, the germans had mach 20 missiles in the 1930's. Nowadays with the guiding systems we have there isn't really any point in going for speed, I'd rather have a supersonic plane that 99% of the time doesn't get detected until it's too late, that can pull evasive maneuvers without turning it's pilot onto a splatter on the window than a hypersonic plane that still can't outrun any missiles but also can't move anywhere but forwards. Just makes it an easy target.
Additionally, the stealth'd be greatly reduced by the massive heat signature coming from the ramjet engines which would just make it more of a sitting duck. I can possibly see the use of a hypersonic drone, but it doesn't have a lot of utility unless you're playing a game of chicken with air defences. Maybe if they were small and stealthy, they'd be able to do decent bomb runs, but we're already pretty good at that, and I doubt we'd be able to reduce the cost of hybrid turbojet-ramjet engines enough to make enough of them to be useful.