Fabric is the future - but everybody does SMB/NFS NOW. It will a few years before SAN has anything like the out-of-the box usability that NAS has right now.
Or before SAN has anything as flexible as NetApp. The 3 SAN presentations I have seen all had one big box of drives that got allocated out at the physical drive granularity and are a pain to enlarge space for a host. You can configure a RAID 5 set within a SAN and allocate it out, but you can't grow that dynamically. Have to unload the data, reconfigure a new set of drives, reallocate them to the host(s), then reload the data. Or burn another parity drive setting up a whole new RAID 5 set as well as configuring the host to recognize another drive device/mount point.
With a NetApp, you can allocate space at the MB granularity with quota trees, let everyone mount the whole filer, or anything in between. To add space, add a drive or a shelf of drives. Yes, you may end up with another parity drive depending on how many drives you're adding (I don't recommend 48 drives in one Raid group :) but that's optional.
Nope, for flexibility (and ease of administration), you just can't beat 'em! Just 2 more cents...