Well I've seen the average age at death in the wild quoted as 10 years. I'd expect a healthy Corn (of any morph) to have a reasonable chance of reaching 15 years old in captivity these days, and many live longer than that.
I guess we won't know the resilience of the newer morphs for a while yet, but Lavs etc don't seem to be exhibiting any signs of endemic weakness at the moment. Obvious health problems tend to be selectively bred out, as new morphs are developed. If nothing else, a reputation for producing sickly Corns would be bad for a breeder's business.
Breeding may well shorten a female's life, and of course there are always the risks associated with conditions like egg-binding. But where that would probably be a death sentence in the wild for most, in captivity they should be given appropriate care and the majority will live to tell the tale.
Breeding generally will sap a female's resources, but I have a 16 year old whom I bred regularly (and who laid a full clutch of infertile eggs every year, even if not mated), so I don't think even that is a hard-and-fast guarantee of a shorter life.