Confirmed: You will be able to hide the OnePlus 6 notch... eventually

"A black-out feature was seriously considered in the early stages of the development of the OnePlus 6. At the time we decided against adding this feature. We wanted to focus all of our time and resources on delivering an exceptional full-screen experience. I still believe the best way to experience the OnePlus 6 is using the full potential of the display. Recently many users have raised interest in having a black-out function. We respect your feedback, and would like to give everyone the ability to choose. This function will enable you to black out the background of the notifications and status bar. It will be added in a future software update released after the launch of the OnePlus 6. Look forward to sharing this new update with you all. Thank you for making us better!"