About enabling experimental features via flags - I hope there will be an option buried in there somewhere for curious people to "go nuts" and enable a large slew of functionality in one step, appropriately warned. I can see that being a pain, but much easier than having to go one by one on obscure features with a non-technical audience.

I love seeing what creative devs are doing out on the fringes, and having to dig around in flags every time something new gets added could potentially get pretty annoying. The benefit of vendor prefixes was this - if you were on a latest version, not just dev/canary channel, there was a lot which was turned on by default, even if theoretically it wasn't stable. That was actually quite a good driver of fresh technique and innovation, seeing this straight away, despite the major hassle of bloated CSS.

It's inspirational seeing people who maybe aren't totally technical being able to get their hands on very fresh stuff without having to completely hand hold them on every step required to get it going.

Really, a lot to be said on this topic, but just wanted to mention this as didn't see it discussed yet.