That wall their testing on? Has a nice metal strip along the side and a metal electrical box. Grab the marker. =D
But yeah, I don't think this will catch on. Something tells me it'll be a little too expensive.
Also, what if you wanted to paint your building? I think the fact that it keeps out paint will not only sop writers from altering the surface, but property owners as well. I doubt they would want to make it so they can't re-paint their building.