Even in latest versions of Pinnacle Studio it might be possible to open old projects and save them to newer format.
Convert Pinnacle Studio 400 project file to Pinnacle Studio video project.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert st4 to stu on Windows
A professional video editing application
Convert from st4 file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.