I've been researching the lower end (ha!, right?) mac laptops to replace a 2009 (yes, seriously) MacBookPro. Then I ran into the "butterfly keyboard" issue (for those who have experienced it, you know about it including the class action suit; however, this problem with dust, sticking, etc is new to me). I cannot find where there is any information, though, on the butterfly keyboard and it being a problem with the AIR, just the MacBookPros, how they'll fix the MBP for you now under a new warranty, and the issue with MBPs, etc.

So, the question is: Does this affect the AIR? and if so, has there been a fix for 2018 models?
I think I have this correct: The issue was somewhat mitigated with gen 2 butterfly keyboards in the current MBPro. The most visible mod was an addition of a dust barrier shield, which seems to be effective in making the dust issue better, and likely as a result, less sticking. There seems to be fewer complaints now than a year or two back. It remains to be seen if that is a long term fix, I suppose.
The new MBAir has what has been called a gen 3 keyboard, now with a bit less noise from the keys. I doubt those new ones are part of the previous repair program for the MBPro keyboards, although if keyboard issues appear with your Air, you should be able to get some attention under warranty. That's something that you could ask about at an Apple store, I suppose. I confess that I haven't spent a lot of time on a new MBAir, but that might be something that you can try out in a shop. It's something that I could live with, but I am not presently looking, either.