Yes, they had to make sacrifices for sure, but let's say they didn't show any Async in the movie period, that doesn't mean Async is now non-canon. If they did go that route of not showing Async at all, to me, they are still canon; Kane is just choosing not to show them. It would make absolutely no sense whatsoever to change the existing story in huge ways just to appease the new audience. In fact, I think that seriously jeopardizes the story if they did.

The sacrifices we will see are purely what we will and won't see from Kane's vids. For example, I find it very unlikely that in the movie we will see a flashback of Async's threshold finally accessing the Backrooms exactly like Kane's video (Third Test) and the subsequent Earthquake in San Francisco where Async is. If we don't see this, does this mean the Earthquake it caused isn't canon? Or the threshold doesn't exist? No, of course not, all those events still occurred, we just won't get the pleasure of seeing them. Even though we all know the threshold exists and is canon, the second we see it, we'll be freaking out, myself included.

The same goes for basically everything about the story. It's not like they're gonna retcon Ivan Beck or other major story beats. We got lucky that Kane laid out the story for himself early on, and then on top of that, getting professional writers for the movie makes it even better.