Small but important reminder that Holmes and Watson grew old. They reached retirement age. Watson wasn't killed in battle and Holmes didn't die at the Reichenbach, but they both survived. They survived the hundreds of mad criminals they went up against too. It's canonical that they became old men, even though that was a difficult feat: both because of their livelihoods and the era which they lived in. Holmes retired to the countryside. There's nothing to say that Watson didn't eventually also do the same.
They didn't die tragically- they lived full lives, and there's something very hopeful about that.















