I don't think it will be too difficult for Apple to implement an always on screen. They are apparently using older 28-nanometer process for the current watches and can switch to 20- or even their newest 14-nanometer process for the next watch processer. They can also still use wrist detection by keeping the screen at 50% brightness and go to 100% brightness on wrist raise. Anyways I still think the next watch has an always on screen. Only time will tell.