>>725126527 (OP)
Steam was ass at first, but then every game company started going towards DRM and the convenience of having everything in one place while also not being anti-consumer made Steam successful.
Competing is hard because Valve has built a reputation of not screwing over or lying to the consumer. There may be cases here and there but for the large part its not part of their reputation.
Competing services like Epic had good ideas with the free game thing but it was too desperate and obvious.
Whoever competes will have to be some third party like gog sortof was and not directly connected to a publisher or engine creator.
Steam also has the advantage that Newell doesn't appear to be in anyone's pocket. Though I admit I haven't well researched this, I'd be surprised to hear that Tencent or something similar has some major control over Valve. Even if they do, its not part of their reputation.
In short, be convenient to use, be trustworthy, prove that trustworthiness over time.