History tells us that dynasties end. They don’t have to end with heads in a basket, like the Stuarts in Great Britain or the Bourbons in France. When Queen Victoria died, Britain’s current House of Windsor took over from her House of Hanover with little more than some messy business around their German royal titles (it was, after all, World War I). The last emperor of China even had a rather vibrant life after royalty. But no matter how things end, the longer a dynasty lasts, the more fragile it becomes.
There’s something similar in sports. If a team has a sustained run of success — like the New England Patriots have had since the dawn of the 21st century — the best it can hope for at the end is a brief slide into mediocrity.