James Mishler operating as Adventure Games Publishing has a license/agreement to produce an alternate version of the Wilderlands known as Wilderlands of High Adventure. It is in fact for C&C. That said, much of the material is system neutral. He probably had the closest relationship with Bob Bledsaw in the last years and is a repository of Bob's unpublished thoughts and ideas. James' work has been released in fits and starts and not all of it is exclusively Wilderlands. As mentioned he is self publishing so his work is a combination of PDF and digest size print.
http://adventuregamespublishing.blogspot.com/
More recently Robert Conley has obtained a license. He too has an alternate version of the Wilderlands. The Majestic Wilderlands is essentially his Wilderlands campaign as developed over 20-years. He is writing for the Swords & Wizardry retro-clone of OD&D.
http://www.batintheattic.com/
I have heard rumors that Eostros Games (the creative force behind Goodman Games d20 Wilderlands releases) would like to work out a deal to do more material. Perhaps things that Greg Geilman had once worked on when employed at Judges Guild.
http://www.eostros.com/
Geoff Dale has been talking about self publishing a giant campaign expanding Judges Guild's Inferno (rights were released back to him).
http://www.acaeum.com/forum/viewtopic.php?t=2352
A manuscript for Tula: City of Mages exists. Who knows if it will ever see the light of day.