Vendors have even WAN access to VDI, so it only makes sense that eventually the idea of using VDI through a cloud service provider would arrive. It has, in the form of desktop as a service (DaaS).
DaaS provides IT the same advantages as local-network VDI -- centralized desktop control and security, centralized data control and security, and centralized backup and disaster recovery for those virtual PCs -- but also eliminates all the capital expense of an on-premises VDI deployment. Rather than buy all that equipment, you essentially rent it from the cloud provider as part of your subscription cost.
In a world where BYOD, working anywhere from a laptop, and working at home are normal activities, DaaS makes even more sense because so many users may not be on your local network, as VDI deployments assume they are.
DaaS of course raises issues of its own, not the least of which is what you do when there’s no Internet connection (such as in some rural areas or secure locations), no reliable or fast-enough Internet connection (such as on an airplane, in a hotel, at a café, or other public location), or an Internet connection whose VPN or other perimeter security keeps you from accessing your DaaS provide (such as from a client site).
One answer is to use a local Windows client when you can’t connect to the DaaS provider, then synchronize later, though that adds complexity to both the deployment and your security posture. But for most people most of the time, Internet connectivity is both available and reliable enough.
Sensing an opportunity, there are now “managed DaaS” providers that do more than host the Windows desktops in the cloud. They also provide management services such as image management and network configuration. Services include Amazon WorkSpaces, NaviSite Managed NaviCloud, Citrix Workspace Cloud, and VMware Horizon. Microsoft also has Azure RemoteApp, though it is not a fully managed DaaS solution but a remote application access tool.
DaaS isn’t a solution for your entire organization, but it is a new option worth considering as part of your VDI strategy.