John Gruber raised an interesting point about the future of Slack after being purchased by Salesforce:

First, my take presupposes that the point of Slack is to be a genuinely good service and experience. […] To succeed by appealing to people who care about quality. Slack, as a public company, has been under immense pressure to do whatever it takes to make its stock price go up in the face of competition from Microsoft’s Teams.

[…]

Slack, it seems to me, has been pulled apart. What they ought to be entirely focused on is making Slack great in Slack-like ways. Perhaps Salesforce sees that Slack gives them an offering competitive to Teams, and if they just let Slack be Slack, their offering will be better — be designed for users, better integrated for developers.

When I first heard the rumour of Salesforce was buying Slack, I really had no idea why they would. The only similarity between the markets the two operate in is that they are things businesses buy, and I saw no points of synergy between the two products that would make this acquisition worth it.

I’m starting to come round to the thinking that the acquisition is not to integrate the two products, at least not to the degree I was fearing. I think Gruber’s line of thinking is the correct one: that Salesforce recognises that it’s in their interest to act as Slack’s benefactor to ensure that they can continue to build a good product. Given that Salesforce has bought Tableau and Heroku and more-or-less left them alone, there’s evidence that the company can do this.

As to what Salesforce gets out of it, Jason Calacanis raises a few good reasons in his Emergency Pod on the topic around markets and competition. Rather than attempt to explain them, I recommend that you take a listen and hear them from him.