léonie is correct about your Mac… it will eventually die and/or become useless. This is how I decided to deal with the issue:
My “working” Aperture computer is a 2009 Mac Pro which reached end-of-life 1-2 years ago (Apple stopped making replacement parts). I run it on Yosemite to avoid the few minor problems that Aperture has with more recent OS’s. Last year, I bought a used 2012 Mac Pro that I use for all my other work — it is now running High Sierra. I use “Carbon Copy Cloner” to copy an updated version of my Aperture library to the new computer every few days (CCC is fantastic!). I don’t do any edits on the new computer, but my Aperture library is available for reference, plus this copy acts as another backup. If needed, I can install Yosemite on the newer computer and use it as a “back up” computer for Aperture if/when my other computer dies.
I am slowly migrating my photos to Lightroom on the new computer, but want to complete a huge project of scanning/editing ~50,000 old family photos (from 1885 to 2003) in Aperture before I use Lightroom exclusively. This project will take ~2-3 more years to finish, so hopefully one, or both computers will still be operational. After that, I will simply use Aperture as an archive and use Lightroom for all my future (digital camera) work.
Finally, I also have been exporting a copy of my final edited jpegs to the “Photos” app on the newer computer. Photos — or some future version of the software — will probably be around as long as Apple exists. I periodically give my family members an updated copy of the Photos library. The Aperture and/or Lightroom libraries will simply die after I stop using them. No one will want to deal with those programs, but the Photos app is used by all my family members. This should help assure that the photos out-live me!
The 2012 Mac will probably be at “end-of-life” in the next year, or so. The 2009 Mac is easily the longest I have ever used a computer. However, I can’t imagine using either computer 5 years from now. You’ll have to face the final demise of Aperture at some point! You don’t want all your photos to be lost because you didn’t migrate to a “living” program!
