I wonder what the server edition will give. Windows 2012 (Windows 8) gave a new filesystem, disk deduplication, better BitLocker (used space only encryption), a chkdsk that could run on a snapshot, and many other improvements. Windows 2012 R2 (Windows 8.1) beefed up Hyper-V, added some nice options to deduplication, slightly better Storage Spaces, etc.
I'm hoping that ReFS can be used as a system volume filesystem (for the C: drive), deduplication can be used with the system volume as well, and maybe some work on being able to isolate programs from each other (similar to how the program sandboxie works, where a program thinks it makes a lot of changes, but all the changes it does are redirected to a sandbox directory.)