I really hope the word e-mail is replaced with something else (like 'memo') and a new paradigm is introduced around the concept of offline discussions, like forum board or stack-overflow.

The purpose of such a system would be to save discussions and understandings in discussions for a long term.

I read Stack Overflow threads now and have a pretty good idea about the thought process from problem -> approaches -> solution, including solutions or approaches that were rejected.

Real-time chat is not a replacement of a meeting, because meetings have substantial outcomes and key decisions taken, that are usually recorded as Minutes of Meeting / Meeting notes.