Chat should be universal, not organization specific
Currently, if a user is invited to another organization, the entire interface reflects which org he is currently working in, this includes both chat and team sections. This causes multiple problems for chat, as chatting with another user now requires you to be aware of the context they are currently working under.
Scenario: User wants to talk to a contractor working on a project for him.
In his chat window, he types the contractors email address. He will be greeted with two matches: an external and a guest account. Depending on which he selects, the message will be sent to different contexts for the contractor .... which will slow his response time. The user has to effectively know what org the contractor is working under. This is a poor experience.
Chat should be more like skype: universal and permanently external. Regardless of which org a user is working in, they should recieve all chat requests. Only the Teams/Files section should be Org-specific.
This allows a user/contractor get invited to other orgs more confidently. While he may not see project updates immediately, if someone were to chat him up or @ him, he would still get the alerts/messages inapp_.
The switching model creates a "blinders model" currently