It's not possible technically to have an expansion pack which adds new content, then lets people use that content without actually having the expansion pack. If someone makes a scenario using dozens of megabytes of new models and textures, they can't be included inside the SCN, and people won't be able to play the SCN without the data.
Things likes more triggers and a unit editor would be possible, but approximately nobody would be willing to pay for those things, so it'd be cheaper for ES to just release them in a patch...
Quote:
LicensedDevil
Forumer
Location: Bucks, UK
Wow, same place as me. Fascinating