That was the interesting takeaway from the Elon Musk talk about how cheap the fuel was compared to everything else. Having the Skylon be reusable then shifts some of the operational costs back to fuel.
Of course a plane that can fly a Mach 5 and 100,000' has other uses, the most obvious one being the SR-71 replacement. Nothing like a bit of high speed aerial surveillance "right now" to help folks on the ground make better decisions. I'm sure someone would pony up the $400M they need.
Yes, but having anything be reusable does that. If you can make up what you would have gained with Skylon by making the fuel tank 5% larger, then the opportunity cost of developing a radically new engine isn't worth it. Mach 5 does have other uses, though.
I don't know the first thing about orbital-scale rocket economics, so, please, regard this as complete and utter speculative nonsense.
My thinking is that, if there's a future where we might have regular launches to orbit all of those costs will have to drop. At that point fuel might just start to become far more significant.
Let's imagine weekly "Orbit The Earth Adventure"(TM) launches in 25 or 50 years. The spacecraft, crews and maintenance would have to be optimized in order to enable the business model. I think it could very well be in that context that a MAGLEV launch-assist vehicle might make sense.
Again, I don't know what I am talking about and don't really have the time to research the subject and learn about the economics of low-earth-orbit manned space flight. I'll just have to leave it at that.
