The Future is Official
Monday 19 March 2018 You can't blame Kanoa Igarashi for changing his nationality from the US to Japan. He is guaranteed to surf in the 2020 Olympics according to the newly released qualification system.

The International Olympic Committee (IOC) recently approved and released the qualification system for Surfing's Olympic debut in Tokyo following the landmark deal between the International Surfing Association (ISA) and the World Surf League in December last year.
Here are the out-takes from the rather confusing and officious document that allocates spots in a descending hierarchy via the WSL, ISA events and continent or region. Basically, there are 40 spots available, with 20 male and 20 female, of which the host nation gets two, one male and one female.
No more than four surfers can represent a country, to a maximum of two surfers per gender as per National Olympic Committee (NOC) regulations. Four surfers into 40 suggests that 10 countries get the nod, if their surfers qualify via the various rules. Countries like Australia, Brazil, and the US won't have a problem. Ten surfers from the men's WSL Championship Tour (CT) and eight from the women's will be eligible.

CROWD PLEASER: Billy Staimand at Surf Snowdonia in 2015. Photo Red Bull Content Pool
A key phrase is "All surfers selected by their respective National Federations for their national teams must participate in 2019 and 2020 ISA World Surfing Games in order to be eligible for Olympic qualification", which means that some CT surfers will have to surf ISA events.
In accordance with IOC guidelines, qualification events have been determined in hierarchical order of qualification as follows:
2019 World Surf League Championship Tour: First 10 eligible men and first eight eligible women.
2020 ISA World Surfing Games: First four eligible men and first six eligible women.
2019 ISA World Surfing Games: four men and four women selected based on their continent. Top finishing eligible surfer of each gender from Africa, Asia, Europe and Oceania.
2019 Pan American Games: First eligible man and first eligible woman in the surfing competitions.
If the slots for the host nation of Japan are filled through the above hierarchy, their slots will be reallocated to the highest ranked eligible surfers from the 2020 World Surfing Games.
Download the full document here