What are the next Android smartphones to be compatible with ARCore?
Is there a known list of future compatible devices yet? Maybe a general project
Here is a list of ARCore 1.4 Compatible Devices (last updated October 19th, 2018).
To your last question around testing on the emulator, as of this week, you now run ARCore in the Android Emulator with a virtual AR camera:
https://developers.google.com/ar/develop/java/emulator
When you are using Android Studio 3.1, and Android Emulator v27.1.10, just create a new Android Virtual Device (AVD) for the Android Emulator that targets Android 8.1 Oreo (API 27) and verify that the back camera is set to Virtual Scene.
(I don't think this answer deserves the bounty, and I also don't think you'd get a worthy one any time soon. But let's roll anyway:)
So I did a bit of a research as to why are these the only devices supported. It's a tough question to answer of course, but we can speculate.
I read through the reddit on the subject (among other sources) and it seems that ARCore does not require some special hardware, but it does require a "calibration profile" per each specific set of camera, sensors, and builds. I.E. each device.
I've found this Medium article about what Apple had to do in order to calibrate their own ARKit coupled with some speculation about Google's calibration process.
WOW! Turns out it's a really heavy task. And it seems that Google has chosen these devices specifically because they've already undergone some initial calibration for other purposes. So it's even harder to start the calibration from scratch.
So... There seems to be mixed news here:
The good news is that ARCore does not rely on some fancy new hardware platform with some fancy new standards that are gonna be hard to enforce in an already highly fragmented market.
The bad news is that unless an automatic calibration process is invented, each device SKU needs to undergo a costly, lengthy and manual process. It's very hard to estimate the costs involved, and even harder to estimates the rewards.
Which brings us to where we started: My guess is that device manufacturers will not be quick to jump on the ARCore bandwaggon. Yet.
It seems that it's gonna take some time before you'd get a reliable answer to your question.
You will get the current list of ARCore supported device manufacturers and models below link.
ARCore Supported Devices
The current list of ARCore supported device manufacturers and models can be found here:
developers.google.com/ar/discover#supported_devices