We are costing the amount of work required to port the J# WFC functionality to 64-bit. The WFC functionality was built to provide a smooth upgrade path from J++ to J#.
If you are using WFC with J# and your application will eventually require 64-bit support, please email me - briankel at microsoft dot com. Please include details of your 64-bit usage scenario. Also, if you're using J# or JLCA and would like to join my customer list (who I semi-regularly poll for product planning inquiries) feel free to drop me a line as well. Tell me a bit about your application and its architecture in your email.