I think almost everybody will agree with this. The pattern is that these "exclusivity" agreements last one year, and then things are wide open. As far as Stardock is concerned, they are a small developer, and making their stuff available in the least expensive way possible probably explains the use of EPIC to start out. Oh well. The best thing that could happen is that the game is wildly popular (my choice) and Steam regrets their terms weren't as attractive as EPIC's. And thus other games will be more likely to go on Steam. In the last year I have seen two excellent games wind up on EPIC...Old World and GC4. I am grateful that it isn't more, I suppose.
I should add that I haven't personally had any problems with EPIC, but that doesn't mean there aren't a lot of people who do have problems. The main thing is having all my games on one platform is convenient. I am embarassed to say how many games I have on Steam, so I won't. Let's just say it is into three figures. Yipes.