Don't ask what you can do for parkour, ask what it can do for you. Everyone's experience with it will be subjective and different; there is no standardized path or progression. Internalize the concept and work with what you find will apply to you best. So what I'm saying is, everyone can succeed in parkour, as long as they remember that everyone is different and what is going to be the maximum utility of parkour for one person will not be identical for another. It will be what you make of it, and therefore age won't matter in the end. Good luck!