SEARS photos were very good. The color lasts and lasts. Some we had taken about 38 years ago are still as beautiful as the day they were developed.
Walmart photos are crap. Photos we had made there began to fade and within five years turned to a reddish color. The blues and yellows disappeared.
What matters is exactly what the color was at each point in the photo. That's just a heap of numbers. Just data. If you can save the numbers, you don't have to worry about whether the color lasts. Because you can reproduce it on demand. Now or ten thousand years from now.
So, if you've got some old Sears photos you want to keep, your best bet is to scan them in at high resolution and preserve the digital images. And remember to spread around copies, because digital images are not indestructible (but terabyte drives are cheap).