Toyota and Subaru are working on their next generations of the 86 and BRZ respectively and it is rumored that the concepts of the next generation cars will be shown at the Tokyo Motor Show next month. The production versions would follow in 2021.
While there is talk of a new platform, it is likely that it will be an upgraded version of the existing platform as neither of Toyota's TNGA or Subaru's Global Platform allow for the size and rear-wheel drive nature of the cars.
Power will still come from a boxer 4-cylinder, but it will be upgraded from 2.0 liters to 2.4 liters producing around 220 horsepower. A 6-speed manual will still be available along with the 6-speed automatic. The change of engines would address one of the biggest complaints about the 86/BRZ twins, namely by boosting power.