It will depend on the game and the studio, frankly. Some may not have positive things to say about the EGS deal 6-18 months down the line for a variety of reasons. For others, they may actually get away with it.Keep in mind that Jeff Vogel has been building an audience since almost a decade before Steam was even a thing.
He might have somewhat of a rare view of what it would cost to go (timed) exclusive on EGS.
But to be honest, I think that people are overestimating the cost of going exclusive in terms of losing part of your audience.
People who promise to boycott (and actually keep their word) are a loud minority at the best of times and utterly insignificant the rest of the time. Some portion of those people who boycott your game for being exclusive to EGS probably weren't interested in buying it in the first place, so they are hardly a loss in any case (case in point I won't buy games on EGS, but I also don't care about most of the exclusives), which further reduces the effect any boycott might have.
Plus, even if developers don’t suffer as a result of taking moneyhats, it’s still worth highlighting that this might be worthless to Epic in the long run.
If only one thing comes out of this, I hope it’s that they don’t make a return on investment on their store.
Plus I still have my principles. I won’t be buying any games that go EGS exclusive.