I don't think anyone can predict the future. I have had alot of dogs over the years, all but one lived till 13/14 years of age, and didn't pass because of a definitive health issue like cancer/etc.. One I had to put down at 9 because of spondylosis. I've never had a dog with cancer/bad hips/elbows or any other genetic disease.
Each dog has probably had one major health issue at a time in their life, but not life threatening (knock on wood), so I consider myself very lucky and for the most part have / had some pretty darn healthy dogs..
On the west coast, and I don't know your location,,I would look at Kim's dogs,
JustK9s | Kistha Haus German Shepherds and Pembroke Welsh Corgi
,,I have admired her dogs for a long time. I know Robin (huertahof) has one or two of them.
There are no guarantees, but honestly, even with the issues I've had , it won't stop me from ever getting another gsd or worrying about the "what ifs"..