I've always thought of Skype as a personal product that was also used for business, and Slack as a primarily business oriented product. I'm afraid if Skype gets more features rammed into it for groupware, then it'll be even more bloated.
That's Microsoft's issue with Skype: they fail to realize that the marketplace determines what a product is.*
If you took a well-known, purpose-built apartment building and converted it in to offices, you know what people would say? "Why would I set up my office in an apartment building?"
Regardless of how good they could make Skype, it's always going to be Skype: the cool thing you use to talk to your brother who's living in Costa Rica for the year.
—
*That being said, if you've done your due diligence and really understand your audience, you can do a better job at creating a product that directs the attention of the user toward the thing you'd prefer.
