Not the OP but I think if free slack becomse unattractive enough people might start to look around. There are enough alternatives (self-hosted like Mattermost,

Not the OP but I think if free slack becomse unattractive enough people might start to look around. There are enough alternatives (self-hosted like Mattermost, Rocket.Chat or free tiers from other vendors e.g. Zulip, Discord). That presumably has two effects: 1. People are used to them and if the decision at the workplace comes up to choose a solution the other product is on the table. Or worse if Slack messes something up with the paid tier people might be more willing to switch to something else that they know already. 2. Every private group chat might involve people who never used something like it before. For these people the software they use first is the baseline. And they are more likly to recommend the solution they already know to a organistation that is willing/able to pay for a higher tier.