Who says it has to be a response to EGS though? Valve does plenty of things behind the scenes and is always advancing Steam with stuff like Steam Proton last year and just recently Remote Play Together. This deal could easily have been just-as-business usual for them regardless of whether the EGS existed or not, we don't know if EA approached Valve or Valve approached EA either.
It'll be dumb if everything Valve does from now on since the inception of the EGS is just immediately credited to EGS because of "competition finally forcing them to do stuff" when they've already been doing plenty of different things for Steam for a long time already.
Yeah, this is something I wish people would get a grasp of, rather than simply assuming this via feigned ignorance. Valve is a business like any other, and thus they conduct their own business the way they see fit. They've been working on games and software tools for years now, but because EA showed up with Origin, or Ubi with Uplay, and certainly not when EG and EGS.
What amazes me though, is people talking about Epic's little contributions of recent times, but not Valve's (like Proton for example, or the recent remote play for local co-op, which is frankly amazing and much needed from all the other clients in the PC space).