are there chromebooks still on shelves this fall that *don't* support Assistant?

for Intel, chrome.system.cpu.getInfo() already exposes modelName, which will look something like "Intel(R) Core(TM) ..." for these processors.

for stylus, see issue 632814.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5a4f574298888fc8d3bcd7babeca9545bd2ff432

commit 5a4f574298888fc8d3bcd7babeca9545bd2ff432
Author: Michael Giuffrida <michaelpg@chromium.org>
Date: Tue Aug 07 01:02:53 2018

Add chromeosInfoPrivate assistantStatus API

Adds a new "assistantStatus" property to chromeosInfoPrivate.get that
returns "[un]supported" depending on whether the device supports a
version of Google Assistant.

Bug:  856719 
Test: browser_tests, manually with eve and another device
Change-Id: I947c7849bbb1f134dde7515e6ea40504d470d69c
Reviewed-on: https://chromium-review.googlesource.com/1157384
Commit-Queue: Michael Giuffrida <michaelpg@chromium.org>
Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581081}
[modify] https://crrev.com/5a4f574298888fc8d3bcd7babeca9545bd2ff432/chrome/browser/chromeos/extensions/info_private_api.cc
[modify] https://crrev.com/5a4f574298888fc8d3bcd7babeca9545bd2ff432/chrome/browser/chromeos/extensions/info_private_apitest.cc
[modify] https://crrev.com/5a4f574298888fc8d3bcd7babeca9545bd2ff432/chrome/common/extensions/api/chromeos_info_private.json
[modify] https://crrev.com/5a4f574298888fc8d3bcd7babeca9545bd2ff432/chrome/test/data/extensions/api_test/chromeos_info_private/extended/background.js
[modify] https://crrev.com/5a4f574298888fc8d3bcd7babeca9545bd2ff432/chromeos/chromeos_switches.cc
[modify] https://crrev.com/5a4f574298888fc8d3bcd7babeca9545bd2ff432/chromeos/chromeos_switches.h