And yes, at least I would hope that if Apple offers an ARM based Mac, it would be close to that MacBook. Though the new Air isn't that much larger.
90% of normal people usage works fine. For coding I use remote desktop to AWS, it's actually nicer to work with than the average laptop because you get so much more CPU power and bandwidth.
Also the Smart Keyboard is simply the best shape for typing on a seat-back tray table.
As always, it's a matter of what's your purpose. As a developer you'll be much better off with a MacBook Air, for that measure, which I think is a much better piece of hardware than the 12" MacBook.
I still think hinged convertables can work even if a lot of the industrial design on existing models sucks.
BTW I could not find the weight of these trackpad keyboards, and I looked. Weight is an important feature and should be listed.
The negative thing with Macbook was the price point. It was a bit expensive to have as a second computer and on the other hand not powerful enough to be the primary workhorse. Also the battery life could have been better.