For most of us our top level is determined by the amount of motivation and discipline we've got, along with the time we have to dedicate to the sport. The genetic ceiling is something you pretty much don't need to worry about, I would just about guarantee that you could grab gains if you did the right type and amount of work. I think the real the question to ask yourself is how much time and energy do you reallllllly want to spend on getting to that next level. Like how worth it is it to you, does the next level look like an extra 5w on FTP or 50w on FTP? Are you OK with potentially having less fun to be more fit? These practical questions have more bearing on what you can accomplish than any theoretical genetic limiter.