Current thoughts:
When 1.8 comes out and stabilizes there will be two servers connected by a portal: Gargamel (and only gargamel) and then the main server with a full normal, nether, skyland, space stack. They will be connected by interserver portals. Gargamel can remain survival server and that means shared inventory and dynamic market. Or gargamel can be switched to creative but separate inventories.