The Lumia 928 is very real, I personally saw it. I was at a Nokia event in NYC yesterday were we had some appetizers, drinks & a lumia 920 to take pics & record the event. Ed Sheeran was performing later that evening. While browsing around the event we noticed a black phone on a tripod, the difference was there was a xenon flash on the back. I then took a walk upstairs to get as close as possible to the device, but the device itself was in a black case, but I think my suspicion was correct it was a Lumia 928. When the performance started everyone had the 920’s recording the event except the gentleman next to me, he had the same square looking device I saw upstairs so I approached him. I asked the gentleman is that the Lumia 928 he said no its a 920, I pulled out my device and said no this is a 920. I then told him the xenon is a dead giveaway as well as the amoled screen, he just looked at me and smiled. I took a few pics of the device I saw but couldn’t really get to the back of the device. Check out the pics below.
In this pic below you can clearly see the charging port and the 3.5mm jack are both on top of the device.