If they try to do it, they’ll only be able to do it on Pixel phones.
I don’t know who was responsible for getting rid of native gestures (Quickswitch) when using fullscreen gestures, but because of this move I effectively stopped using 3rd party launchers, especially Nova Launcher, known for not supporting Quickswitch.
I only use Pixel Launcher Extended, which fixes many annoyances of Pixel Launcher.