We have developed a couple of back-up scripts to pull out data like 'tasks', in the event a PM comes to the PMO Group indicating they have completed destroyed their schedule, and does the PMO Group have a 'back-up'. We can then provide them a spreadsheet of task data of what it was the previous day.
What your client is asking for is migration scripts for all aspects of PPM, in the event, they 'terminate' services. Sure, they could be build now, and maintained going forward when different versions of PPM are provided, attempting to guess what the replacement application data requirements are. Or alternatively, they wait until the decision to terminate services is made, and they know what the data requirement is for migrate the data.