Update - 6/24/2015 -- my phone arrived back via UPS today. They returned my exact phone (the IMEI and serial numbers are the same as my original box). So that's good. I guess I am happy to have my old phone back rather than a refurbished one.
Also interesting -- they included a packing slip which seems to say they replaced THREE parts on the phone, not just the camera. The packing slip lists the following parts:
Part #GH96-07482A - ASSY CAMERA-MODULE 16M AF 1/2.6" SM-N910
Part #3009-001678 - AUDIO-RECEIVER; 132DB, 2.6, WB, RECTANGLE, 12
Part #GH96-07542A - ASSY SUB PBA-SUB (SM-N910V); SM-N910V, SUB
Looks like the first item was the camera, but no clue what the other two items were. Audio receiver? Hmm. My phone didn't seem to have any audio issues when I sent it in. Maybe they found another problem during troubleshooting? Or maybe they need to replace those other parts in order to fix this issue? No idea.
One annoying thing -- my phone had a nice ($30-ish) Zagg Invisible Shield glass screen protector on it which was installed by the Costco rep when the phone was new. The screen protector was semi-permanent -- it was stuck to the screen with adhesive....so it wasn't something that you could just snap off and snap back on.
For some unknown reason, Samsung removed the screen protector and sent it back stuck to the outside of a bag containing the stylus and rear cover, but it was otherwise just loose in the brown cardboard shipping box. Because the back of the screen protector was super-sticky, it is now covered with small particles from the box which are embedded in the adhesive. This basically ruined the screen protector. Obviously this is Samsung's fault, so I may try to chase them down and see if they will do something about it. The screen protector came with a lifetime warranty and it says they will replace it as the result of ANY damage, so maybe Samsung's negligence counts as damage?
Oh, final comment -- the camera seems to work fine now. Of course, fingers are crossed that whatever parts they replaced are better quality than the ones that failed.