Skylon is the frontier of launch vehicle research with literally 1 TRL(Technology Readiness Level), and it is more difficult than the Space Shuttle project. The project would cost estimate of 12 billion dollars, and the development of SABRE is only at the beginning. With heavy competition of other companies, (SpaceX have just launched their reused boosters), is it just a matter of time that this project would be cancelled?
It's plausible enough that companies like BAE Systems and organizations like ESA have invested in the technology. BAE Systems' interest lies in defence applications of the SABRE engine, so we'll probably see those long before Skylon gets off the ground.