We know how that works
"Slack continues to enjoy a greater share of the market in spite of the gang at Redmond flinging out a free edition of their platform to get users on board"
Of course Microsoft is doing that. It's Market Capture 1-0-1 : hook the greatest number possible on the free version, then transition them to the paying version.
Or kill it and propose a new product that does the same thing, but you have to buy it.