Debian will probably continue on its way of becoming a desktop user distro.
I know I'll get crucified on Slashdot for saying this, but in my experience, Windows works OK at being both a desktop and a server distro. You have people using Windows 8 (yeah, it needs Classic Sell or something but that's a UI issue, not a fundamental OS problem) for desktops and Windows Server 2012 for servers, at an enterprise level. This doesn't seem to cause problems, and those 2 OSes I just mentioned are basically the same OS with different features turned on. One time a place I worked gave my Windows Server 2012 on a laptop I was to use for development (don't ask me why). The funny thing is, after I disabled some features and enabled some others, as well as installing some libraries, I basically had a Windows 8 desktop machine.
Is there really a need to have "server-oriented" and "desktop-oriented" OSes in this day and age when we have plenty of storage space, or can we have one OS that can just be configured to behave the way we want it to?