Since writing my last piece, some Googlers reached out and said my assessment was largely correct. The Andromeda part was clearly wrong, though, so I will try to rectify that.
Based on code like this that was pointed out to me, it looks like Andromeda might be tied to Android's free-form window mode for laptops/2-in-1s and possibly tablets. Though my initial article incorrectly conflated the two independent efforts, Andromeda and Fuchsia will still eventually combine together as a laptop platform. I think the app “chrome” will probably look like Android (because they will be Android or eventually Flutter apps), but with floating windows and elements of or even an overall UI similar to that of Chrome OS. Supported inputs would be mouse or trackpad and keyboard, and possibly touch. Not necessarily wildly different visually from Chrome OS today, in other words, but using the Android API. Andromeda may also explain the “Chrome OS will merge into Android” claim originally made by the Wall Street Journal. The underlying OS will still eventually be Fuchsia, though.
For those wondering about ARC, it was kind of a failed experiment. It sort of worked, but it didn’t really prove to be a workable solution. I really don’t want to get into this any further here. And as stated before, NaCl looks dead.
I think the Android API and runtime will continue to function as before on all Fuchsia devices, except now the underlying OS will be Fuchsia, and the kernel will be Magenta, not Linux. And then there would also be Mojo, Flutter, etc. at least starting on Andromeda devices. It’s hard to imagine pushing both Flutter and the Android API forever, though. Android will likely gradually have to fade away (over many, many years).
Back to the more important point: yes, Fuchsia will be Google’s new OS underpinning all its consumer devices eventually. I think both a “Pixel 3” laptop (or whatever this hypothetical product would be called) and the Pixel 2 smartphone will probably eventually run on top of Fuchsia, but I make zero promises as to anything shipping at any particular point in time, because I have no idea. Still, that is my suspicion based on public commits.
And again, if Google doesn’t break compatibility with the Linux user space, yes, it really can swap out the Android kernel (Linux) for Magenta/Fuchsia, and leave the Android API in its place. Standards like POSIX do exist, after all. Here is some code pointing to exactly that. (Updated thoughts.)
And here as well is some “proof” about Fuchsia replacing Linux (in extremely deliberate scare quotes):
Pink + Purple == Fuchsia. “Pink” is a reference to Apple’s Taligent operating system (which ran legacy Mac OS apps on top of a microkernel). “Purple” is Project Purple, the original iPhone project.
Sure sounds like Fuchsia will run Android apps on smartphones to me! (Yes, engineers working on ambitious special projects love to make witty references, and I think these Apple-related ones are really classy and ace.) Andromeda also happens to be a type of Fuchsia plant, which may be a coincidence. I remember the Purple reference from last year, but didn’t know what Pink referred to at the time. And I never thought to connect these references to Fuchsia being able to run Android apps on a modern smartphone platform. Major kudos to Zargh for connecting the dots! (Click the links for his explanation of the references in greater detail, but I don't really want to draw even more attention to the engineers for the sake of their privacy.)
And as someone on Hacker News once again commented: “ANDROid + chROME + DArt = ANDROMEDA?” I would doubt the Dart part though.
Lastly, I will again note efforts such as A/B (seamless) updates that Google added in Nougat, which may help out with the Fuchsia transition. Crazier things have happened. Samsung once migrated Galaxy Gear owners from Android to Tizen, for one.