Here is a decent article on genetic potential, I know there are a hand full of formulas that help you find out your genetic potentials. Clearly if you let your hormones get back to normal your going to slowly lose those gains. Your body can't hold onto it its just not possible. Professional Bodybuilders are on HGH, Insulin, Gear amounts in a month that many dont run in a year. Most people wont even see their genetic potential without gear and once your there you definitely need gear to go beyond that. I think what people are trying to tell you is that people will see gains, and can maintain them up until their maximum potential, once you hit that, you can hopefully cruise around that and build a little bit each time your on cycle. You also don't lift for hytrpophy because your only interested in strength not size. Your not going to add 20lbs every time but hopefully you can add 5-10 your first few cycles until you get to your max once you get there AAS is the only way to go beyond that. With out HGH, Insulin, IGF, MGF, GHRP you can't add cells you can only expand and cause hytrophy of the muscle you already have.
Please note that this is a very informal post and my opinion
http://www.bodyrecomposition.com/mus...potential.html