Not much to be said. But Facebook has done a very good job so far of taking the steps required to own communication. Although in the world of enterprise, Slack is killing it at communication.
I don’t think that Slack will stay in enterprise. I don’t think the company will make the switch to something more consumer focused - I think it will happen because Slack is that good. Private Slack chats used for entertainment are on the rise. In a recent Designer News thread about which sites to visit when bored, Slack chats were mentioned along side PH, HN et all. I believe this will only become more common - I know I’ve asked similarly minded friends to join Slack because I want to be able to chat with them casually throughout the day.
We spend a lot of life at work - and need to communicate a lot while we’re there. Facebook knows this. They made Facebook at Work for this very reason. In the same way that very few people viewed Google as a place they would go to socialise (one of the reasons I think Google Plus failed), most people don’t think of Facebook as a place they’d make part of their workflow. I think trying to get significant adoption in the enterprise space with the Facebook brand is naive.
I don’t think buying Slack is.