Yes

This will be a slow transition, but an important and inevitable one. Citizens should also do the same.

Great, now the ecosystem needs funding to smooth out the rough edges.

Let’s go

A Matrix server is a good solution. You can disable federation if you would rather not talk to other instances and have a similar experience to Mattermost, Slack, etc.

If you dislike the Matrix protocol, an XMPP server would work exactly the same way.

NextCloud Chat could also be a viable solution for internal chat.