At a previous employer, I implemented a virtual desktop environment technique for the purposes of configuration isolation and software IDE isolation. Unmet performance expectations probably contributed to dropping the idea of firm-wide implementation. Things have since changed.
XaaS in the cloud and VDI will soon be the competing paradigms of IT infrastructure. Both will have their place and could exist harmoniously within the same organization. The true disruption will be the conventional desktop workstation deployment/configuration/maintenance that voraciously consumes cost/labor/management resources. The difference between the mainframe era and this one is the granularity of service model choices. IT managers can choose an all-in-one solution or build their own a la carte. The possibilities are there but the innovation, the change in perspective needed, is still developing.
With 3 cloud topologies, public, private, and hybrid, then VDI becomes viable. Firms that are very protective of their data or will not accept dependence on vendors for their own SLAs will select private or hybrid types. Whether justified or not, perceived characteristics of public clouds still raise concerns: security, reliability, redundancy.