@hamel: I can’t speak to your exact license situation, but from a technical standpoint there is a way to publish a Windows app on the web. Linux support multi-user connections and has no CALs. What you could do is create user accounts on Linux, and in the Xsession file instead of running a desktop, just run a rdesktop connection back to Multi-user Windows and their software applications. Using rdesktop on Linux, you can publish a whole desktop with Start bar or just run one particular application. Rdesktop also can kick into fullscreen mode with no window manager, so it will consume the whole pane of NX.
We have many Windows applications deployed using NX on Linux in a similar manner. We purchased User CALs instead of workstation CALs, which allows users to connect from any end device and gives you more freedom.