Upload & Sell: Off
As a business, I guess it depends on your workflow, customers and volume.
Hard drives are relatively cheap, but shooting up to 200,000 photos per day at some of our larger (youth sporting) events, with customers who's purchase window is about 1 year - the shelf life on 95% of our photos (1-2 million per year) is less than two years - after that we delete master sets that haven't sold.
So 22TB of data drives, with another 22TB of offsite backup data drives, and the servers to house them, does get to be a cost center with the rare possibility of somebody wanting a 5x7 after a few years.
At some point, you have to ask yourself what is it worth to keep old files for an extended period of time. Again, volume and customer expectations.
Otherwise, we rely on our photographers to get rid of 'non-sellable' shots before they leave the camera.
However, when it comes to personal photos, yes, those are kept indefinately!