This is my thinking on the WED roadmap:
WED 1.1 will relatively ship soon, without cosmetic and usability improvements. At this point the basic bugs (import/export) are fixed, so best to get out a finished, stable build so that people can at least edit overlays.
A future version will provide editing ATC layout information for X-Plane 10. This shouldn't be too hard to get working, as we already have this in WED now so that we can develop test data for the new ATC system.
A future version will provide usability enhancements (e.g. previews of facades, etc.). I don't have a ton of code done for this yet, but it's important for everyone using WED for pretty much any purpose.
A future version will provide road editing since X-Plane 10 can drape roads.