From the spectator's point of view, I still think the English premier league and other European leagues are more popular. The Arab leagues and Chinese leagues are emerging but they cannot take the place of the ones already running for ages. Yes, the players want to play for Arab Leagues as they offer attractive packages but still i will not believe that Asia have become supremacy in football as yet. They may never become as there are very few Asian countries that play quality football.
It is a gradual process. First, the players will shift to the non-European leagues. Once that is done, gradually the fans will shift their allegiance as well. EPL still remains the most popular football league in the world. And that is because for many decades the best players in the world have participated in this league. If the Saudi Professional League wants to challenge the English Premier League, then it is going to take at least one decade to so that. That said, challenging the EPL is not on the agenda for the Saudis, AFAIK.