I had a great grandparent live to 102. 3 of my 4 grandparents lived into their late 80s with the oldest passing a month shy of 90. Even my grandparent who smoked 2 packs of cigarettes a day lived to 78. For all of them, their last good year was about year 80.

My dad just turned 78 and has really slowed the last 5 years. Longer life says little about quality of life.