When a company stops supporting the product, should they release source code so community can support it?
If it turns out the product is unsafe through unfixed security holes should you be able to get a refund?
Maybe.. OnHub has a command-and-control network in the cloud, with which you interact using the Home (formerly: Wifi) app on your mobile. I guess they are ending support for OnHub control protocols in the cloud. So you'd need to replace the software in the router such that it could be controlled some other way.
Right; personally I'd be quite happy if the EOL process was "here's all the needed source code to build a kernel and trivial userland, and steps to build and flash a firmware image that boots a busybox shell but doesn't have our management binaries" and then let the community do whatever they want (since that's basically what you want in order to repurpose the thing or build OpenWRT for it).