Yep already know that LG 18:9 Samsung 18.5:9 OnePlus 5T 18:9 Pixel XL2 18:9 to name a few however my hope is it’s something that will change in the future.
I think instead you'll see video change. Obviously movies and TV are unlikely to change their standard (in the near future); but I think you could see YouTube and even Netflix go to 18:9 or 19:9 as their standard as the majority start using the new phones.