Fellow accessibility features users:
One of our brilliant Chromebook Central TCs (Hi, I'm Will) has reported that An adjustable cursor (mouse arrow) size has been implemented in M59 canary. Here is a screenshot that Will shared:

Currently there is a simple choice of the normal size cursor and a large cursor. Those settings are found under Settings > Advanced Settings > Accessibility Settings
Stable channel ChromeOS should reach Milestone 59 sometime around the middle of June 2017 at the current pace. There is no guarantee that this new feature will be included in Stable Channel M59 or included exactly as it currently is since there is understandably a lot of tweaking etc that occurs as new versions of ChromeOS wend their way from Canary > dev channel > beta channel > stable channel. But if all goes well, by mid year we should have this new capability in stable channel ChromeOS.
YAAY !
And of course for those of you who are more adventurous, you could switch to beta channel to see the new developments approximately 1.5 months earlier and assist Google in the feedback/developing process.
Thanks to Will for sharing this !
-jw
PS: Will is not super shy or anything, he is just waiting for his application to this Accessibility Testers group to be approved. In the meantime Will offered the screenshot for me to share here.