I suppose for now I may stick to Gajim (and Conversations on Android).
Nowadays we use zulip at work which has a better model (topics). For IRC I use quassel because I can have the backend running on a server and when I connect using the frontend I see the channel history and messages I might have received weeks ago...
I understand that the Pidgin community is small, so claiming that "the other protocols will eventually be supported" seems unrealistic. This change requires the community to take on unnecessary porting work and we are already dealing with constant protocol changes, playing whack-a-mole with protocol providers.
For instance, this guy [1] is doing incredible work, but I doubt he will want to invest his time in unnecessary rewrites unless someone steps in to assist with each plugin.
The pidgin project is 25 years old, and libpurple is 17 years old. It's entirely fair that a rework is required, and much appreciated that this work is continuing.
So at a bare minimum we needed to totally change the way messages work. Which inside of a chat client, is a pretty big change. That obviously led to other changes and so on and so on.
As for the other protocols... We needed something to prove out most of the abstractions and trying to prove out abstractions while implementing multiple protocols is a ton of work. But on our radar are new XMPP, Bonjour, and even a Matrix plugin. All of these will be coming from us and will be in tree.
That said, there will not be any proprietary protocols in our official source tree. If you want more information on that, check out this post [1].
As for Eion's plugins, I've been talking to him through much of this as you would expect. Obviously his time is precious and we didn't make this changes to spite him or anything, but we (me specifically) have offered to start porting his protocols for him.