iPhoto Shared Albums After Death

Any subscriber should download the photos they want to keep as soon as possible.

Shared albums are not meant to be used as a permanent storage. If there should be a problem with one of the shared photos aor the photos do no longer sync properly, we may need to turn off the Shared iCloud albums to reset them. Then only the photos that are still in iCloud will return to the shared album.

I hope you are well and your question is about an event in the far future. Your shares albums will remain in iCloud as long as one of your Apple devices is still signed into iCloud with your Apple ID. You may want to take the precaution to set up a legacy contact, so one of your heirs can access your cloud documents and data: How to add a Legacy Contact for your Apple ID – Apple Support (UK)

And just in case you might want to include specifics in your will or directive.

How to request access to a deceased family member's Apple account - Apple Support

Good luck for your scanning project. I am very glad my father had scanned all the old prints of our family photos. They are a treasure I am still saving and enjoying.