Comment by codebolt

Yes, they will run, as will most VB6 apps from 1998.

But if you have developed a .NET Framework app that you want to see living into the future a decade or more from today, you need to know that maintaining it is going to be increasingly painful as time goes on. You are locked to an old version of the C# language, and you absolutely can't count on third-party dependencies to stay supported. At some point MS might well decide to drop tooling for .NET Framework development in new releases of Visual Studio.