The latest release of Docker for Windows ("Docker Community Edition 18.06.0-ce-win70 2018-07-25") has officially deprecated AUFS with the following notice (https://docs.docker.com/docker-for-windows/release-notes/#docker-community-edition-18060-ce-win70-2018-07-25):

AUFS storage driver is deprecated in Docker Desktop and AUFS support will be removed in the next major release. You can continue with AUFS in Docker Desktop 18.06.x, but you will need to reset disk image (in Settings > Reset menu) before updating to the next major update. You can check documentation to save images and backup volumes

I'm thinking it's probably sane for us to follow suit and have 18.06.x be the final release that supports AUFS (especially since it repeatedly makes kernel upgrades / choosing a kernel version challenging).