According to VentureBeat's editor and popular Twitter leakster Evan Blass, the first Developer Preview release of Android 9.0 should arrive in around two weeks. Although there are a lot of name-related speculations, he only named "Pumpkin Pie" as a personal preference. Other desserts that could turn into Oreo's successor include Popsicle, Pecan Pie, Pastry, Popover, Pandoro, and Praline.
https://www.notebookcheck.net/First-Android-P-developer-preview-supposedly-coming-mid-March.287392.0.html