Is there an article or something that talks about the fifteen year time jump? Any details are appreciated!
I believe it’s based on this IMDb page (credit to @selina-meyer for pointing it out).
Now, as a general rule IMDb casting pages should be taken with at least a grain of salt, but the age of the actor cast to play Little Richard is at least indicative.
Admittedly, I can’t find any bio information on the actor to work out his age with, but going purely by his appearance, he must be playing age fifteen or so at the youngest. (Odds are that the actor is quite a bit older than that – one of the chief reasons teenagers are always cast with actors in their twenties is the strict working limits placed – entirely properly – on younger actors)
Bear in mind though, a flash forward could be nothing more than the final scene – Little Richard caring for Selina in her dotage – so it doesn’t necessarily follow that we’ll see EVERYONE fifteen years on.