Bazzite exists because of SteamOS, and SteamOS is Arch-based. If there's a danger of one OS starting to dominate, I'd still think SteamOS is more likely because it has Valve's backing.

I don't think there's much danger of all other distributions disappearing any time soon, even for gaming applications.

What I hope is that container-based atomic-type distributions take off. I've been using Linux for decades, and it's such a nice change to have an OS where I don't have to fiddle with drivers or the base OS.