Coming 2 America has been a sequel idea in development for quite a long time. It's one of those concepts that we knew had been considered as the script was worked on; it simply took a long time to make ready for the screen. Any movie that takes that long is going to go through many changes as it evolves, and Coming 2 America is certainly no exception. While the core story has remained intact, Eddie Murphy recently revealed to CinemaBlend that originally the plan was to cast Tracy Morgan as his son.
Coming 2 America sees Eddie Murphy's character of Prince Akeem discover that he has a son, which results in him returning to America to connect with him. That core seems to have always made up the idea for the sequel, but as Eddie Murphy explained to our own Eric Eisenberg, at the inception of the idea, and for several years after, the expectation was that Tracy Morgan would play the role of the son. Murphy explained...
Tracy Morgan was gonna be my son. Three years into writing it, Tracy was the son, still. What changed was, we met with Tracy a couple times and was like 'Tracy look the same age as me. How are we going to make this believable.
To be sure, selling Tracy Morgan as the son of Eddie Murphy would have likely been a tall order. Eddie Murphy is only seven years older than Morgan, and, while they both look pretty good for their age, Morgan doesn't look so young that he could easily pass for Murphy's son. Instead, the film ended up casting Jermaine Fowler, nearly 30 years younger than Murphy, as the son. What's more, Tracy Morgan took a role as the boy's uncle. It's certainly a more realistic place to put Morgan. It's understandable why one might want to cast Tracy Morgan as Eddie Murphy's son, but even for a comedy, there's a suspension of disbelief issue that would likely make the entire movie feel strange.
Of course, one has to now consider just what a version of Coming 2 America with Tracy Morgan as the son would look like. Jermaine Fowler is funny, but Tracy Morgan has a pretty unique style he brings to his comedy. And you can be sure nobody was planning for him to play against type in Coming 2 America. In the trailers for the film we see Tracy Morgan's loud character colliding with the much more reserved Prince Akeem and we can only assume that originally the plan was for the sun to be that way.