I came across something called Fuchsia by Google that is rumored to replace androind. There's no Linux in this new one. There's a prototype online that you can try in your browser. Looks pretty good. Just search for it
Fuchsia is not a good replacement. Google is pretty bad at design, and they are sluggish at new meaningful features. This OS wants to get rid of OEM overlays. But that's what I like about my device. I hate stock.