It's early days. I imagine emails (if any) will come later. The user base is probably pretty huge if you include those that still have legacy products. In 2010 Cakewalk turned over about $10,000,000 from sales. Not sure about recent years, but that gives some indication of user base.
A lot of people are attributing the loss of Cakewalk to poor sales etc. I don't think that's the case. Gibson is in such big debt that they simply can't afford to keep Cakewalk and have probably sold all the product code to Microsoft as it so happens that Microsoft is just starting to develop a DAW.