Nah, it won't be abrupt. It's actually already been slowly under way for maybe 2 years.
Floyd doesn't have the same speed and reflexes and stamina as a few years back.
He looks good, very disciplined to keep himself in magnificent condition all these years, but who knows the real state of his body after so many years in an extremely strenuous contact sport. Boxers are trained to conceal injuries.

His superior technical expertise will allow him to continue to compete.
It's textbook stuff, he's very well-schooled.

If a guy has that part down and he's a boxer type, then it makes for longevity even after the physical prime has passed.

Roy and Floyd were both physical marvels of speed and reflexes, but Roy didn't have the technical skills to fall back on when his athleticism and speed eroded: Floyd does.