Ummm, I know you were making a joke, but my pugs were quite active through 15, and the one that made it to 17 was still very active. They were the most active pugs I've ever seen. But we gave them a huge back yard to play in for virtually their whole life.
The one that only made it to 16 did 'go downhill' after 15, and that's why we finally 'put him down.' Blame my wife, she kept him around probably +6 months too long. It took some conversations with the vet to 'let him go.' He was eating less and less, so it was time.
But our 17 was in outstanding shape and his bloodwork and vitals were excellent at his last check-up just 2 months earlier. He still 'ran around' with me in our back yard, albeit at a slower pace, but still, 'jogged' and 'walked' with me. Heck, we just took him to Road Atlanta for the weekend prior, and people kept asking how old he was, and didn't believe he had just turned 17. 10 days later he had the 'neurological event' and we only put the money into saving him because he was in such outstanding shape for his age. Otherwise we would have put him down without trying.