Air launching has been around for awhile, see the Pegasus rocket system as an example. The White Knight is another system. The main goal of much rocket development is cost reduction, and air launching is a way to reduce the size and complexity of a rocket by using an airplane to get it part of the way. So far all the aircraft used for air launch have been manned (B52s and L1011s).
Manned aircraft have to have a certain size and complexity in order to provide a pressure vessel and support systems for the squishy organics inside. This extra complexity and size adds significant design and build cost. Manned aircraft need much more certification because of the safety aspects, adding to the design and build cost. Bigger aircraft need more fuel, bigger engines, etc adding to the build and running costs. This proposal uses advances in pilotless aircraft to reduce the size and complexity of the launch platform by making it unmanned and unpowered (except for a small rocket engine). It essentially outsources the design, certification, and build of the manned, powered aspect to a 3rd party. You don't need an astronaut or test pilot to fly the towing airplane because it's commercial off the shelf - some extra training and similation would certainly be required but not to the level that someone flying the White Knight would need. Because there's no people in the lifter-glider if something goes wrong the towing aircraft can just cut it loose over the sea. The rocket could explode and the tow would simply fly away. A small rocket on the lifter-glider would boost the glider into a better drop angle for the rocket and get it clear after the drop, which would be harder to accomplish on a manned airplane. All these aspects mean you could possibly reduce the price of high-altitude launch.
The term "game changer" is often over-used, often to get more budget. Whether it is appropriate to this proposal is opinion-based. I see potential to this proposal, at the same time there's a lot that would have to go right with it. Towing a big glider with a rocket on it using a big jet is a bit different from towing a sailplane behind a super-cub! The towing airplane might require significant modifications to handle the stresses, and that could make the proposal much less financially attractive. I personally think this is worth investigation but I'm not dancing a jig just yet.