We cant know what would have happened as it didnt. I would guess we would be stronger under 1 banner with many governors.Short term, yes however it was probably their time calling them and allah is the greatest of planners and in the long term we would have been more weaker centralized and would have trouble withstanding attacks from the likes of genghis khan if he just had to break us from our capital, Luckily there were several caliphates and for our case the mamluks in Egypt able to protect us which is the good thing of having several allied caliphates which are harder to destroy and better govern their actual constituents
We lost a lot of people to Genghis because of disunity.