I am currently working on an environment that is roughly the same size. We currently use NetApp so there are alot of NetApp tools that helped us overcome storage growth with desktops mainly the de-dupe and rapid cloning utility. - We are not using linked cloning
The other thing to keep in mind is your VMkernel config, it is best to try and setup as many targets as possible on your NAS device and configure load sharing on ESX to take advantage of multiple targets, maybe do 300 - 400 VMs per target IP, reducing the possibility of saturating the gigabit target. (assuming your not running 10G yet)