Yeah, that would be the one major stumbling block. Hosting peoples artwork, demos etc would need a lot of space.
However, I think the main point of a WIP area is for people to have a dedicated place where they can post their WIPs and look at other WIPs without having to clutter up General Discussion, or have problems finding old threads, because they will all be in one nice little area. So if space is a problem, we can just add an extra forum and keep the same rules as now with regards to attaching files of limited sizes.
Any larger files can be hosted by the person themselves and they can provide a link.