They deliver all the amp-ads via that single piece of js, and will share some of the revenue with the publishers. It's not a bad idea after all, if only they had presented it for what it is: a Google fork of the Web. The "performance story" is just the bullshit.
I think it's nothing so sinister as a "fork of the web", but a badly thought out approach of going back to faster loading web1.0 by recognizing that quite a lot of JS adds no value to the end user.
It may not be so sinister because it's a badly thought out approach indeed. Although they got quite a few big partners already, this undertake requires rewriting the whole Web which is too much to ask even if you are Google.
But please tell us more about the business model, I see you're a Google employee.
Same as before, just with happier users including myself. Happy users are good for business in the long term.