It looks like we will have another digital storefront coming on the scene as Epic Games will be launching the Epic Games Store very soon. This new digital storefront will be made available for PC and Mac to start, while other platforms will be added throughout 2019. At launch the store will offer Fortnite alongside a set of hand-curated titles, what those titles might be is currently unknown.
So why would developers put their games on the Epic Games store? Well to start the Epic Games store will only take a 12% cut (compared to the 30% cut Steam takes), giving developers the remaining 88% of sales revenue.
If a developer is using Unreal Engine the 5% engine royalty will be waived by Epic and instead is factored into their original 12% take. So if you have your game on Steam and it uses the Unreal Engine you are giving away 30% to Steam and 5% to Epic due to the engine royalties. So moving from 65% to 88% is a major increase in earnings for developers. It also does not matter what game engine developers use, the revenue split will remain the same.
So it looks like Epic is ready to take on Steam, but the big thing will be luring gamers away from Steam. I guess we will see what happens when the store launches.