Universal may not be hurt as much as the others you mention. I am bringing up Universal has the theme park rights to Nintendo IPS and is one of the lands coming up for Epic Universe.
Nintendo has been a huge name for video games for 40 years starting with Donkey Kong in 1981. Nintendo in general is something multiple generations heard of. Mario, Donkey Kong, Metroid and Zelda got their starts in the 80s. Nintendo starting Mario Kart, Pokemon, and Kirby in the 90s.
Nintendo for IPS is as big as Harry Potter in my view for Universal.
I only can speak from an IP standpoint since I never went to Universal in my life.
Agree that Uni is in a better position. But I still don’t think they can standalone as the primary destination. It’s easy to spend 7 nights at Disney. Uni, at least for me is a 4 night max trip. That will change when Epic opens. How much it will change? We don’t know yet.