I think there’s some confusion in how those base images are used. You don’t have to have templated images, if your base image works across all devices (eg. if a base image is made for
armv7hf devices, instead of one specific platform).
resin/rpi-raspbian image you are linking to is pretty orthogonal to Dockerfile templating, and that image is widely used outside of resin.io as well, so definitely won’t be removed. You can use that image if you want to without any templating on a Raspberry Pi 3, for example (as far as I know, just not optimal).
The templating should be pretty clear that it works on the image name level, and only works when deploying on resin.io, since it’s custom tooling. Will review the templating docs anyways, to see if we can even further clarify things.