Another question is, how would you transfer your data if you bought a new drive.? I'd hope you can copy ~500mb at a time by swapping the drives back and forth. Get your saves, critical files, etc.
Very good and difficult question. Swapping the drives back and forth is error-prone.
Maybe a kiosk service at retail partners - bring your old HDD, they sell you a new one, transfer the data and buy back the old? Or PC program to transfer them to a PC with 20 G of free space and back to the new disk?
I doubt they'd go to so much trouble, anyway. Only a small percentage of advanced users will want to upgrade.