There is already a whole lot of information about the plans for the next edition of Pathfinder. If you want to get the lowdown but you don't have a crystal ball, these links might give you a glimpse into the future. Playtest will start in August 2018 but you can catch some early demonstrations at UK Games Expo. Second edition launches August 2019.
Paizo are publishing the playtest as a free PDF, but if you are thinking of buying hardcopies of the Pahfinder Second Edition Playtest then here is a list of games retailers who are taking advanced orders. Paizo have made it clear that they won't have time to re-print and get delivery of these items before the playtest is over. So pre-ordering will be necessary to secure a your copy. Deadline: order before 1 May 2018.