The problem is how do you lower launch costs "by a factor of 10 or higher".
You seem to be think the solution is to develop scramjet technology and build launcher which uses this technology.
Scramjet technology may or may not "be the answer". But IMO this is very similar to the idea of fusion technology may or may not "be the answer".
In My Opinion the problem with both these ideas is MAINLY that the government is attempting to develop these technologies. Now, it is quite reasonable to assume that only government could attempt to develop either of these technologies because it's the only entity willing to risk the millions to billions required (and the only entity ALLOWED to be involved in these areas).
I think there is no hope of the government developing low cost RLV, though lots of hope if the government "creates an *proper* environment" in which the private sector could lower the cost of getting into space.
-gb