We have some very successful ISVs in the UK using ... drum roll... Foxpro very successfully. I spotted this article covering off the future of Foxpro. I found the most interesting bit to be the promise to use www.codeplex.com to allow the Foxpro community to continue to enhance some elements of Foxpro.
"Instead of releasing new versions of FoxPro, Microsoft will release core portions of the FoxPro software to its CodePlex community development site, said Alan Griver, a group manager within the Microsoft Visual Studio team, which leads the FoxPro team."
Turns out there is already a very active Foxpro community on Codeplex - check out http://www.codeplex.com/VFPX