Delicate Dog Question

My dog Trotter will turn 10 tomorrow. He’s still as spry and ready as ever, but as he approaches the end of his first decade with my wife and I, a big question has forced itself to the front of our minds: Should we bring another dog into our family while Trotter is still game so he can show the new puppy how to be a great dog?

Trotter at his dirty best

On one hand, Trotter has had ten years to figure out how to be an esteemed member of our family while retaining the noble dignity of his breed, that is, a mostly healthy amount of independent thinking. A puppy would learn how to act in no time with a “father figure” to show him the ropes, and Trotter’s legacy would not be confined to memory; we could enjoy and interact with its sentient form.
On the other hand, there’s this: 3,594 days of Trotter. Just Trotter. He’s the show in our house, and he knows it. Sharing all he knows with another dog may disrupt his next decade (yeah, I know) unfairly. My worst fear is that a new dog would change Trotter in the last half of his life and besmudge the memory of my best friend.