I have heard that the royalty paid to the manufacturer is about $0.50 per kit. The royalty is paid in multiples if there are other brand names used in the kit. For example, if the car is Ford, the tires are goodyear, the driver is Earnhart, and the NASCAR emblem is used then the royalties ar multiplied as everybody wants their share. This is why a plane model, without all the product names is about $15, and a NASCAR model with a driver identified is about $20.
The time delay for the new Ford models may be that Ford is holding out for the highest bidder. The Revell/Monogram Mustang model is already been anounced and should be on the shelves soon. The model of the GT should not be far behind. I have heard that the contract with Shelby America has been or will be signed soon so the Shelby Mustang model will be produced soon after the real thing is released.
If you look at models of cars about 15 years ago you will see "Goodyear" or Firestone" on the tires, and you would commonly see decals for other common items such as Fram oil filters, Moon eye hubcaps, etc. All this is gone because EVERYBODY now wants a piece of the pie. The manufacturers no longer consider it "ADVERTIZING" to have models of their cars "out there".
The problem began because a kid got hurt building a model and the manufacturer of the real thing got sued because they have "deep pockets".
One last thing and I hope you find it interesting. There is a die cast model of the new Ford GT in 1/18th scale. I have heard, but have not been able to confirm, that it was produced and sold without Fords permission, that is it is illeaglly being sold. Fords legal department put a stop to it so it is no longer available.
Think about it. All this fuss over little model cars. Have you noticed that the model manufacturers are making kits of things prior to about 1970? Both model cars and model airplanes are being made of the older cars and aircraft. Now you know why, the older stuff was not copywrited or tradenamed. No royalties!