This needs to be bumped up more especially the part where you talk about the degradation/erosion of RAP. Theres no way it could be continuously reused everywhere as the OP stated/implied. I used to do quality control and testing of hot mix asphalt, in the plant and in the field, and the quality of the RAP being used was extremely important. The highest percentage, in NY, that I saw, was somewhere around 15% and this stuff had to be tested regularly. Granted this was 10yrs ago so new developments have happened but even so.

Especially in the tristate (NY, NJ, CT) where roads are subjected to high and low temperatures and constant use, effectively eroding the aggregate and asphalt binder, RAP taken from them can be very brittle to a point where you could press it to dust with your fingers. Using too much of it would ruin a mix effectively decreasing the life of the road it's being used to pave. The amount of water/moisture the RAP maintained from just sitting in piles was also an issue with HMA.

Recycled tires were just starting being used when I stopped doing QA/QC and that had some other issues. Using it for base and binder levels were fine I believe, but the oils that the rubber took in from years of use was an issue when it came to how effective the asphalt binder was able to stick to it and hold a mix together. It's also not used in the friction layer if I remember correctly since it would effectively lower the coefficient of friction in colder and wetter weather. 

Again I did this stuff 10yrs ago and I'm sure different methods and use has been developed, but from the things I've seen rap was mostly a huge money gig for the plants and increasing its use did not always increase the quality of the road.