Anyone in this situation will want to save PDF files of the tax returns with worksheets), and save backups of the PDFs, and maybe save printed copies.
Any version of Turbotax will only open the year it was designed for. It can import the prior year to start a new return but it can't open an older return.
Because Apple deprecates older versions of their software faster than Microsoft, it is more likely that Mac users will run into the problem of older versions not installing on new hardware, even if you have the CD or the installer disk image. And older versions that were previously installed may not run after a major OS update.
