I'm genuinely excited that you're in this space now, too, as I myself have had my nose to the grindstone building out what the collaboration app for distributed teams that I've always wanted. We need options/competition in this space; just this year alone, I've had a little over a a dozen conversations with interested folks in teams across the United States working in industries from agricultural sensors manufacturing to game studios for hire, and the same pain points that you and I were reasoning about back at Slack are the same pain points that users still unwillingly tolerate.
See you around--and good luck out there!
PS. As an English major I'd be remiss to not share that I love the name emdash. :D