I'm hoping they go for the bigger battery just to support 120 Hz. And the day I get my new iPhone I will be turning the ProMotion feature off to gain superior battery life on 60 Hz![]()
They'll probably make the feature efficient enough (see LTPO) that making it an option isn't necessary. It might actually be a net win power draw due to scaling down to possibly even 1 Hz (it does on the Apple Watch).