The reason that NavCan can display weather as an overlay is because they use a translucent layer principle. It was developed some eight or so years ago.
A further development of this is the translucent windows system where aircraft can not only be seen under active windows but also addressed through the window. If you go to google and type in "translucent ATC windows" you will probably see some of the work being done throughout industry. Malta, by the way has translucent weather data, but working on a different principle.
Forgot to add that there would be a possibility to display around four levels of weather along with their base and top levels.