I usually tell them that Microsoft is simply not creating new versions anymore. Unfortunately they forgot to create a vaiable alternative to the strengths of VFP. Therefore we wait for the next wave of new technology (in regards to dynamic types languages) as we don't see the current strict type .NET languages as a viable alternative. Walter, about 4-5 years ago (when you were making the same argument), there were a small # of people who answered questions in the .NET forum. Today, there are people posting answers in the .NET forum who, 4-5 years ago, were only working in VFP. So it's funny how people are managing to make the switch, are able to build applications using .NET/SQL, even with these "glaring" deficiencies.
I'm not saying that I don't find the language features in .NET 4.0 and beyond to be trivial - they seem interesting - but this concept of "no viable alternative" isn't consistent with reality.