Don, I am truly sorry about dropping that support without notice. The way the Google Store advertises it, it should have "retained version 10.3" which should still work on your device. You just won't be able to get anything new from us on that device. So, per Google's note, they told us that you'd still be supported (via 10.3). It appears that for you, this is not working.
So we didn't send out the notice given that Google told us that our previous version would remain deployed to devices like yours, while at same time, this only impacted only 2-3% of our users, as 97%+ of installations were on non-old devices. Obsoleting your device was forced on us; but failure to send you a notice was our fault. We should have done better.