I propose adding "Absolute Page Number" as a text variable. Similar to Last Page Number, "Absolute Page Number" would allow the document creator to place the absolute page number of the layout onto a page while also using another page numbering system (sections, roman numerals, etc.).

With long documents now both being used in whole or separated into parts by clients, this would allow InDesign users to fulfill the issue of having a page carry two numbering schemes at the same time.