So, as some context, I use Apple, Windows, and Linux systems all in good measure for work, but mostly Apple and Linux. I'm excited to see the M1 Air for all sorts of reasons. I'm excited to see ARM providing hard competition in this space, and excited to see the Air/ultrabook form factor get attention again. I'm also frustrated because I'm tired of seeing these sorts of developments be leveraged to push all sorts of problems with DRM and privacy. Ideally I'd like to see this same thing be offered but with linux or BSD, or at least under owner control.
Having said all that, anything pertaining to battery life I'm skeptical of. In the products I've used, the battery life always declines over time, and in my experience Apple products have been the worst. I love my Macbook Air, but similar dramatic improvements in battery life were touted at the time I bought mine, and I've not been impressed over the years. Sure, at first, the battery life was amazing, but then not too long after I obtained it (a few months or so) the battery life dramatically declined. My Dells, in contrast, started out with less impressive battery use, but declined much less, so after about a year, the battery life was about the same: the Apples just started out great and declined dramatically, and the Dells started out less great and declined less.
There's reasons to think this might be different, but so far the devices haven't been around enough to really speak to me about the long-term battery life patterns. I'm hopeful and open-minded but also skeptical.