I believe the situation has changed now and it will be Valve who will have to compete. What I mean by this is that bigger players are coming and they are throwing money around. Prices will have to be more competitive and Valve will have to cater more to offset these type of exclusive deals. Yes, Valve has the better overall service but if enough top games do not come to their store at the same time gamers will go where the games are. Once Epic is feature complete with Valve, then things gets even worse.
I dont think there's much they can do about moneyhat deals, not that it matters because we're not talking Xbox360 type of Moneyhatting against PS3 - these are small scale because they are 6 months to 12 months long and not like a generation's worth like what happened with Dead Rising, Saints Row, etc
There hasnt been a single game that is on EGS that wont be coming to Steam (excluding Fortnite which Epic owns and possibly Ubisoft games which are already better price value than what Steam or EGS offers in the first place due to the example I provided in my previous post above).
However incentives to buy games on Steam have already happened such as what happened during the Lunar Year sale where they offered a discount on top of purchasing a certain amount of games, something that they never have done before and something that third party resellers usually do.
So as a consumer, this is a huge win for my wallet.
EGS is gonna have to step up and like GOG (where they had a policy to be against VNs only to be reversed due to the success of VNs on Steam) they are gonna be forced to make changes to the policies they mentioned when they first arrived - such as in their stance for support forums, user reviews, cloud saves, etc and of course third party key selling - these are all things that Epic said that they wont provide because they believe "Steam has too many features".
They'll eventually be pushed by Steam's success and all the dirt that is being thrown at them by the overall PC gaming community and will provide them - overall in the end I believe its gonna be a Win win situation for all PC gamers.
Epic's gonna have to do more than moneyhatting 6 month or 1 year exclusivity to have a edge over Steam. Something like getting PC exclusivity over console releases (i.e. console versions getting delayed for EGS release) - I can see that happening and if so that is gonna be awesome!
I also disagree on with what you say is gonna get worse, I think its gonna get better because Valve will definitely improve the service on top of what they have been doing these past 10 years - Origin and Uplay are better than what they were when they first were released, now they mimic'd a lot of what Steam has and its been a great experience. Its only gonna get better for the PC gaming market going forward.