This is one of my non-ranting dislikes of Microsoft. They're dumb. They end-of-life products which people still use.
The #1 reason why I think that Microsoft can not kill Unix based systems is that their products have too-short of a life cycle. Microsoft stops supporting a product after 10 years. An enterprise level accounting system can take five years to design and implement, that's half the life-cycles of the underlying platform! Our last hospital system was in place for thirty years, and took six years of design work to replace the core. It will be another two or three before the ansillary systems are replaced. And with banking, it's even worse.
IBM, on the other hand, still supports systems made back in the 80's because their customers still want to use these products.