A peaceful death
Again, spoilers for the last build
Amazingly, Devon's promise was true: they lasted 110 years.
On Cameron's end, the Echo episode made the finaly years painful, but pain was nonexistent with the love of his life by his side.
They laid together in bed, nuzzling one another.
They both knew their lives were fading, strength sapped from their limbs, Cameron feeling life energy fading, but they could only smile.
They kissed, then went to sleep.