I think if you are on a free tier and your business depends on it, you should anticipate for changes in said free tier. If you want guarantees, you need to be a paying customer.
I agree, but what's happening here is largely not businesses behind the exodus, but loose organizations like open source communities.
You could argue that these are freeloaders and not Slack's problem, but I'd be wary about sending so many users running into the arms of their competition. Part of the appeal of Slack was that I could use one app for everything, which is increasingly not the case.
