We are indeed moving away from `docker.local` in Docker for Mac. There have actually been two networking modes in there since the early betas: the first one uses the OSX vmnet framework to give your container a bridged DHCP lease ('nat' mode), and the second one dynamically translates Linux container traffic into OSX socket calls ('hostnet' or VPN compatibility mode).
Try to give hostnet mode a try by selecting "VPN compatibility" from the UI. This will bind containers to `localhost` on your Mac instead of `docker.local` and also let you publish your ports to the external network. One of our design goals has been to run Docker for Mac as sandboxed as possible, and so we cannot just modify the /etc/resolv.conf to introduce new system domains such as ".dev".
We've been iterating on the networking modes in the early betas to get this right, so beta9 should hopefully strike a good balance with its defaults. It's also why we've been holding a private beta, so that we can make these kinds of changes without disrupting huge numbers of users' workflows. Your feedback as we figure it out is very much appreciated!