Final Fight is officially part of the Street Fighter Universe, while Rival Schools isn't (again, Sakura was just a guest character).The chairperson ("iincho") learned saikyou from Dan (by mail lessons). It IS part of the same universe, they just tried to not make it too obvious to avoid difficult questions on canonicity.
It's easy to guess 5 takes place before 3, Dictator is here and 3 was supposed to have simply moved on and abandoned Shadaloo, implying it was finished. From there, it's an easy guess that 5 will bridge both plot lines.
If I struggled to the end of my determination, to the end of my way of life with my followers, if the result is ruin, then this ruin is inevitable. Grieve. Shed tears. But you cannot regret.