Exactly, think a few years ahead, UE could become a real alternative, when extending into distribution and tailored network framework territory, to separate UE from the competition. This would make things so much easier when you have one resource to learn / deal with instead of third parties. Epic could build upon their existing experience in those regards based on titles like UT and Paragon.
And many successful company titles do not rely on Steam (LOL, Blizzard games, WOT etc), showcasing that alternatives are feasible and rewarding.