With the coming release of Affinity Publisher I don't expect there will be any more updates/fixes for the legacy PagePlus programs. Thus, as operating systems/hardware is updated there will come a time when PagePlus people will be out of luck. Telling them to keep using their existing PagePlus stuff is not, in my opinion, good customer service. They are and have been a customer, encourage them to upgrade and move to the Affinity product by providing an open/import function for the old files. It may not exactly handle 100% of the features of PP, but if it covers say 90% that is a lot better than having to start at square one and re-create an old layout.
My experience has been that software publishers usually provide a way to open/import their own previous file formats, but also those of their competitors, so as to bring in the largest customer base possible. Serif may not want to provide for competitive file formats (for which they would have to discover the file structure) but they certainly know the file structure of .ppp files. To open/import a .ppp file and create, for example, an 8 page side fold document, to be printed on letter size paper in landscape oriention, with 0.5" margins all sides, and text boxes of certain sizes in certain places, containing text in certain font, color, size, and certain pictures in certain places at certain sizes would be a big step in the right direction. As this old document is going to be updated, you change and reformat the text as needed, and change the pictures, but the basic layout is in place and you can tweak things as needed. Easier and faster than opening the old document on one screen, and step by step recreating it on another screen manually looking at old properties, inputting property values in the new document and copy/paste the old text into the new. I did this with several documents that had been created in Microsoft Word and I wanted to have new versions in PagePlus x9. It is very labor intensive.
I urge Serif to rethink their position in this matter. I think the benefit would outweigh the cost, and keep a lot of existing customers in the fold!