In fact, the previous world champions were only European national teams and Uruguay, Brazil and Argentina from South America.
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, but the best football is still played in Europe and South America.
In recent years, very good football players have come from Africa, such as Salah and Mane, but the African national teams are not yet at the level of the best national teams in the world.
Therefore, the inclusion of additional teams from Asia, Africa and North America will definitely reduce the quality of the world cup.
No doubt about difference level between Europe and Asian or Africa, almost on FIFA World Cup edition Europe national teams always dominance and success lead until final although on FIFA World Cup France have loss from Argentina. For Asian and African national team seems qualify until semifinal like Morocco is the best achievement and Asian national team have longer time can't qualifying to higher stage in World Cup except edition 2002 where South Korea have success lead until semifinal.
Hope next World Cup have final team from Asian or Africa because have longer time not any national team from Asian or Africa and Europe or America always dominance in World Cup final.
The reason for European dominance is their interest in football from small ages like schools , colleges universities they have been football at All level and after that their are training academies for football so that's why they produce world best teams and footballers .
Unfortunately this is not the case with African and Asian countries.