I must say, I really am quite shocked and appalled by the posts and attitude towards the breed. No, the breed is not 'too far' gone.
My apologies for my first post, I confused a number of posts as being additional posts from the first poster.
We have had Cavaliers for almost 25 years now, and I am yet to come across half of the issues you have mentioned that are apparently 'common' for the breed. All of our dogs have lived to anywhere between 10 - 15 years of age. As a registered breeder, I know I speak for the majority of the Cavalier world when I say we breed to improve the breed and erradicate known health problems.
I find it almost incredible that you have come across so many Cavaliers with such a dramatic display of health issues, and wonder whether the health issues you've seen are in fact from pedigree dogs/registered breeders, or perhaps puppies purchased from pet shops and backyard breeders, who do not health test or screen for the wellbeing of their puppies.
The reverse sneezing as you call it,is something that is common in many Brachycephalic dogs (dogs with short noses) - not a genetic, or significant health issue.
It is unlikely that you would be able to purchase a show quality dog as a pet (conforming to your standards of coat, shape, size, movement etc) as these dogs are kept by their breeders to better the breed.