Also, those dashboards are misleading. For the North American market the proportion of older phones is less than half of what the dashboard displays
https://developer.android.com/about/versions/oreo/background
You've been able to avoid dealing with these changes for a while now by simply building against an older SDK, but Google is in the process of restricting the ability to put any app built with an older SDK on the Play Store. I think you already can't list new apps that use an older SDK, and existing apps won't be able to update to new APKs using older SDKs starting in November.
FWIW, I understand why they made the changes here, and they are user-positive, and just abandoning Android over them seems like an incredible overreaction, but speaking as someone who has been updating an older app to deal with these changes, there are some real pain-points here if you're bringing forward an older app.
So, some developers will probably defer handling the changes until November, and then if there is some critical bug (security or otherwise) they won't be able to just fix the bug without also building the rest of the app with the new SDK as is, broken/untested even if it compiles?
According to most app stats I've seen (mine and others), Android 6.0+ is pretty much on 80%+, with Oreo nearing 40% since Samsung started rollouts.
Where exactly are you getting this data from? Please do not put random numbers without citing sources.
Couldn't care less about someone in Somalia using Android 4.4 when 80% of my users are on Oreo.