I'm pretty sure that both Warners and Sony also originally announced they were using Dolby Vision but when their discs actually materialised there was no Dolby Vision on them, so let's hope Universal deliver on their promise.
Yes you're right, The Peanuts Movie had a Dolby Atmos soundtrack... of all the films to pick for your first Atmos title. It looks like Deadpool will be their second Atmos title, which is better news.
I've just noticed that Sony have announced a 30th anniversary release of Labyrinth on Ultra HD Blu-ray with a Dolby Atmos soundtrack. Dammit I only bought the Blu-ray after Bowie's death! Come on Fox, where's the Ultra HD Blu-ray of The Abyss with a Dolby Atmos or DTS:X soundtrack?