At least on my hardware Skype and Teams are much more responsive than Discord though. And the laptop's coolers get the workout of their lifetime whenever Discord spins up.
They'd probably turn this IM into family friendly safe bay with strictly moderated content - because let's be honest, nowadays anything goes in. Discord accounts at first would be offered an optional merge with MSA and in long time, you'd have to log into using MSA credentials only. Microsoft Discord branding would arrive. There would be a business oriented version created and MS would abandon Teams; basic Discord would have ads related to your activity - you could avoid that (along with telemetry) by purchasing a subscription as the current monetization options would be removed. A special version with github/git related features would be created - for free, but only for those who are really using it in code related tasks.
Yes, but Microsoft would probably prefer to offer such subscription among own plans - like 356, and that would also happen after Discord would get Microsoft branding. It's a pure guess of course but I think it could happen.
Deeper Xbox integration, probably. Microsoft knows the writing is on the wall that Xbox Party Chat usage is way down and a lot of it has been replaced by gamers with Discord.
They know it so well the new Xbox Wireless Headset essentially has a "Discord feature" though obviously not named or marketed directly as that. (It supports dual pairing with a bluetooth phone for "phone calls over game audio", but everyone I know got the message between lines that it supports Discord chat, and were talking about the headset precisely because of that feature.)
Microsoft would have bought Discord for the gaming community and pursued tight integration with the XBox ecosystem. Which could have boosted the platform, but probably not in a way that resulted in a lot of direct revenue.
The S-1 will reveal all, a tight integration with Xbox and not a lot of direct revenue may still ultimately result in a sustainable and viable product, once you go public indefinite quarterly losses don’t get saved by the next funding round at higher valuations.