According to Serbian daily newspaper Sportski Žurnal (and they're usually very informed when it comes to things like this), the qualifying process for the Tokyo Games will be completely overhauled and much simplified.
World Cup is gone and instead we'll have World Qualifications mid-next year. The top 24 teams from the World rankings on January 1, 2019 will be divided into 6 groups of 4 teams using the serpentine system. The winners will qualify automatically for the Olympics. The remaining teams will have to qualify via their respective continental qualifications, with one team per continent quota like previously. European qualifications should be held in January 2020.
This sounds way too simple for FIVB and their love for impossibly drawn out and convoluted tournaments. I'm not sure how I feel about it.