I have about 20 app demos, mostly for Windows Mobile but some for Windows CE. They were all created in Visual Studio 2008 for Mobile 6.1, Mobile 6.5, and CE 5.0. They are a mix of C# and VB.NET. I've been asked to update them.
I've done a fair bit of research, and I understand you can't do the standard Visual Studio project conversion, but is there anyway to salvage these projects? Ideally, I need to get them running on the current version of Windows Mobile/CE and compiling in the current Visual Studio. Is there any hope for them?
The latest version of Windows Mobile/CE is WEC 2013, and is supported in VS2012 and later. Note that for .NET CF development you will need an Application Builder SDK from the device vendor.
Whether you will be able to port the applications really depends on what they do.
For instance, one of the main differences between CE 5.0 (and its mobile derivatives that you mention) and WEC 2013 is that in WEC 2013 user mode code can no longer access hardware directly, so if the applications rely on direct hardware access you will need to find or implement device drivers to do this. On a related note, P/Invoke is always a potential cause for concern when porting.
You'll also need to determine if the target device includes all the OS features that are required by the applications. Remember Windows CE / WEC are componentized OS's, and the device vendor might have excluded features from the OS image that the applications need in order to function.