The Epic First Run programme allows developers of any size to claim 100% of revenue if they agree to make their game exclusive on the Epic Games Store for six months.
After the six months are up, the game will revert to the standard Epic Games Store revenue split of 88% for the developer and 12% for Epic Games.
It’s a fair concern, but I don’t think anything has remained exclusive on epic, they all come to Steam eventually. If that changes and epic starts incentivising permanent exclusivity, then I’ll be upset. But as it is right now, I have no issues with epic.