Microsoft has a new product in the works called Skype Teams- and it's a bit like Slack.
That is to say it's an internal communications tool for businesses which is designed to make it easier to get in touch. You can set up channels for certain groups and dip in and out of them with a clip and the Microsoft version will also come with all sorts of fancy Office integration using Word, PowerPoint and more.
Slack is a very popular tool and one that is spreading to more and more companies of late, so it's hard to know if a competing product from Microsoft can really get any market penentration. It does have the advantage of being a part of the Windows ecosystem, and you can be sure the product will be pushed pretty hard by the OS for any business customers.
According to MSPoweruser, Skype Teams will also have video calling (which comes as no surprise) and the all important method for adding GIFs and emoji.