Epic, Bethesda, Electronic arts, blizzard all push there own games out with our own digital distribution now. There is no reason for any of them to continue to work with steam. There was a time when it made sense for them but now the cat is out of the bag. Its everyone for themselves or making deals like bugle is with blizzard where they do distribute instead of steam.
Triple A games can go suck a dick, I hate their shitty distribution platforms and use them only when I am forced to. Steam DRM sucks, but apart from that they have given indie developers the capability of wide distribution, and I don't see that going away any time soon.
This.
Also, Steam competitors from AAA studios are rubbish. No-one will ever have Origin, Uplay, Bethesda.net, etc. as their main source of PC games, and even the publishers know it, that is why these clients are parasitic organisms that cling to your Steam purchase from the studio.
The future is indie and half-indie, and Steam remains the best platform for that (if you ignore the frauds and asset flippers that infest the service). The big studios are going down the drain with their gambling-infested repetitive releases anyway.