Sure. Forking open-source projects is a long and time-honoured tradition. If one day Google's terms for participating in the OHA become too onerous, the group will split and part of the group will probably start with wherever AOSP left off. Microsoft will probably woo a few companies with whatever their mobile OS is at the time. Amazon, Samsung, and Huawei are all examples of companies of their toes in the water with their own OS and/or ecosystems.