Here are two progress shots of me on Musclemania stage. The first one is from 2011 and the second one from 2015.
Both shots almost look identical.
I am 1.5kg heavier in the 2015 photo at the same % of bodyfat as 2011 photo. That is only 1.5kg of muscle in 4 years of grueling training and following a dense nutrient diet plan.
Gotta love natural bodybuilding. smile emoticon
The reality is that after 15-20 years of consistent training you do tend to reach the peak of your natural physical potential.
What happens next? Does it mean that you stop improving?
Not necessarily. Even though you may not notice much change on the scale, with the right training and nutrition your physique will constantly be changing on a way that it becomes more refined, and the muscles become denser and more prominent. A term often used in the bodybuilding community as 'muscle maturity'.
Consistency is the number one key that leads to result. As long as you keep training and back it up with a good diet you will keep improving. Most importantly enjoy what you do.