It is my prediction, when humanity explore the stars, and if we haven't discovered FTL travel, each planet populated by Muslims would create their own Mecca, due to various reasons: a sense of identity, practicality, and so on. It's kinda hard to face Mecca when Mecca is on another planet.
This would lead, and this is only a theory, multiple planets with multiple Meccas. There will be debating, and arguments, and the headbutting, and all of this will lead to the heresy fun times that Islam dealt with in the 8th to the 10th century. It would lead to much theological conflict, until everyone calms the fuck down (like the Muslims in the middle 10th century did) until people just kinda accepts
different schools exist.
This may surprise some people (and some Muslims) but Sunni Islam, as we know it today, with all the Hanbalis, Malikis, Shafiis, Hanifis schools didn't exist until sometime until the mid 11th century. The heresy mostly involve a lot of arguing, with certain clerical groups supporting sultans who follow their vision. It's nowhere as !FUN! as the Protestant Reformation and the wars that followed, but it's the closest thing Islam has to it. Sure there's the odd school like the Ahmadiyyas, but Islam isn't as varied as say, Christianity is.
OR nothing much will change, and more schools will pop up, merge, go extinct, with only the minimal shanking. Either way, I should totally write this down for a future story.