To be honest with you in my office and most offices I work in, if they loose local switching they loose phones, and access to all applications and databases. At this point you should pretty much send everyone home. Citrix,Vmware View, and windows terminal session broker all support HA/Fault-tolerant clustering options on the back in. Throw in a duel controller replicated SAN and you can push 5 9's of fallibility all the way down to the desk. Get 2 hour replacement support on switching or standardize and keep a spare. Virtual desktops reduce management, and downtime ins a massive way. I used to work in a SMB with 60 task workers, who after we went to virtual desktops with no-moving-part thin clients I had so little support work to do that I quit, and recommended that I not be replaced.... Its true RDP sucks for a lot of things, but if you have sufficiently fast storage on the back end and use modern protocals like PCoIP, HDX, or the up and coming remoteFX you can have a true desktop experience (I even played starcraft 2 over RemoteFX).

There's an app for that... Wyse Pocket Cloud does vmware view (PCoIP) quite well, and we are testing it for a client. They get a thin client that has crazy battery life in a nice touch screen form factor (and it works with keyboards just fine...). As a wireless thin client the iPad beats quite a lot of the competition in terms of ease of management, battery life, form factor and cost. We are putting them into production for a client and strangely they make sense. As for the whole USB port/hub/lots of things to go with it, if you need those just use bluetooth but really if you need them you should be deploying a notebook. BTW, no one uses NX and X11 for a "Business tablet" however i'm certain there are already apps that will speak those. It is a myth that apple has no inroads in the corperate market, I'm replacing blackberry BES servers for iphone/Exchange active sync left and right. C level execs demand that their iPhone work.