One more thing we should keep in mind is that this program will only get downloaded and used (after we can get Blizz approval) if there is a good use. It should probably have a more social aspect to it as well, so it has more uses than just the custom maps. There has to be a long-term value to it for people to bother (see Steam, Origin and UPlay).
And it would need a decent amount of maps to use it.
Also what would happen if people played it without the program by just downloading the map on Battle.net? What kind of problems could arise from that is a thing to keep in mind.
Overall this might be a really cool thing for SCU though. I bet they could make good use of it.