I put 178,000 miles on my Tahoe and it was still running well when I sold it. I had replaced the stock brake rotors and shocks and head gaskets and water pump and the tie rods and ball joints but this was too be expected and far cheaper than buying a new SUV for $60,000.
Most people are going to smaller and more fuel efficient SUV's and the trailer manufacturers are producing lighter weight models as a result. Not really the end of the world to have the Suburban 2500 go out of production. There is always the Ford Expedition if you want a huge SUV.