The WebRTC functionality isn't being removed, just the built in video chat/sharing that was powered by Telefonica.
You can still use a site like https://talky.io/ with Firefox (and I expect there are other sites) if you're looking for Skype or Facebook alternatives. I don't know if there are WebRTC sites that have sane address books, but I would hope so. I've heard talky.io works well, but haven't used it.
Session setup is a real showstopper if there are no builtin contacts. If I have to paste the talky.io URL first with <some-other-chat-program>, why not use <some-other-chat-program> in the first place?
I know I can email (where I have an adress book) the URL, but why use another communications channel for call setup.
Because <another communications channel> is the channel that every user already has set up with the user they want to chat with. It varies for every person, so why not let them use what is most convenient for them?
Nothing's stopping anybody from writing a walled garden site that provides a nice ui for messaging contacts you stored in an address book on top of that.
You can still use a site like https://talky.io/ with Firefox (and I expect there are other sites) if you're looking for Skype or Facebook alternatives. I don't know if there are WebRTC sites that have sane address books, but I would hope so. I've heard talky.io works well, but haven't used it.