The fact is that African and Asian football has progressed significantly in recent years, which can be seen in the examples of the success of South Korea in 2002 and Morocco last year
Japan and South Korea are teams in Asia that have experienced a lot of progress, especially Japan, not because they were able to beat Germany but being able to qualify for the knockout rounds is an achievement and Iran also a power team from Asia, this is quite surprising because the country's conditions are not so conducive, but the national team can still play in the World Cup.
Saudi Arabia is working hard to develop their league but not sure if it will directly impact their national team because as far as I can see the development only affects the popularity of their league. With the increase in the number of participants, Asia will also get an addition but I'm not sure that there will be a new team that will impress because Europe and America have always been the best in the World Cup.
In due time, those national teams that were added in this upcoming World Cup will be a threat to the heavy teams that exists right now. For now, a lot of them are still developing their teams while acquiring some experience by participating in the upcoming World Cup. Just a little steps and maybe soon, who knows, maybe Asia will also be included into the discussions as they can manage to develop a strong team that will be on par with the top teams we have.