In our pilot, the WYSE terminals have Windows Embedded installed on them. They boot to a local Windows session, the browser auto-opens to the Juniper login page, and the user signs in. After that, they get a list of their applications right in that Juniper window, and launch their XenDesktop session from there.
This method requires an OS on the terminal capable of launching a Citrix shortcut just like any other PC would. It may not be quite as slick as the next scenario, but it retains all of the benefits thin clients (other than perhaps having to pay for Windows licensing).
The way I think you and your Citrix consultant my be thinking is that the terminal boots to its basic OS which has the Citrix integration feature installed. This would be configured to point back to your environment to automatically load the XenDesktop session, more like a PXE boot scenario - where instead of pulling the boot information from DHCP it pulls from the Citrix configuration on the thin client.
If this is what you have in mind, I *doubt* the reverse proxy could handle it, and there isn't a Juniper feature to directly support this as far as I know. There may be a design using the new Pulse client that I'm not thinking of, however.
