You know, I don't know if there is really a criteria for establishing a new breed. I don't know what organization is out there to monitor and regulated all breeds being established. The only governing bodies that I know of regarding breeds, are breed specific.
It is kind of a scary thought...I have heard of Back yard breeders trying to come up with their own breeds.
In one way, it is cool the possibility to make new breeds is out there, but in another way, SCARY (over breeding poor quality horses to try to be a pioneer for some breed)...it is not the responsible people you have to worry about in these situations. I really like the idea of the Pintabians, but when I think about how many generations of horses had to be bred to make a 99% arab the rest paint horse...I wonder what happens to all those generations that were the building block to the breed, but not actually the breed....I also have to guess breeding stock (non colored) Pintabians much be in high numbers, and less desired, so what happens to all of them?