Don't let the industry movement persuade you into thinking that you must have a private, public, or hybrid cloud. Take a look at what is practical in terms of providing quality service to your users. Building a VDI solution for 100 users is very different from building a VDI solution for 10,000 users. Some or all of these may not work well in the cloud. Always do a Proof of Concept before you get ready to commit to a production environment. Although VDI is a compelling solution, it is still in its infancy, and improvements are continually being made. Follow what some influencers are saying about VDI including Brian Madden and Douglas Brown, as they know all about the pitfalls of VDI and aren't afraid to talk about them.