Keep it simple
Providing all users with individual hardware is unsustainable. The control and management of the thousands of machines is difficult as end users are unpredictable.
Our VDI project has been successful because we created a workstation that uses a defined set of applications and user persona is limited. This is the first phase of our deployment and as I mentioned before has been very successful. We are converting existing old hardware using an in house developed windows form as shell and running the boxes into the ground. We will be replacing them with thin or zero clients as they fail. Applications that can be virtualized are and they are delivered to specific user through AD.
Licensing will, as it has always been, difficult as software providers mature to this methodology.
IMO, it will only be a matter of time until VDI is everywhere including accessed from your home.
The technology will continue to mature until the struggles of the hardware past are a distant bad memory.