I agree with you, that the future of Desktop Linux are the atomic Distros. They are more stable and require less intervention, so they can be used more easily by less knowledgeable users and users who prefer a stable OS(in the non-breaking way, not no updates). Making Linux more accessible for new users, is exactly what Linux needs.
I disagree on your view about the Fedora atomic spins, especially universal blue. Who cares if the underlying OS downloads as one big image. It all happens in the background, you don’t notice that. Everytime you reboot, you are on an updated system.