" with the battery instead worn at the waist to prevent the headset from being too heavy." - in my younger days, I'm ashamed to say I was proud to have my camera, PalmPilot, and Motorola Razor hanging off my belt as a badge of geekiness. I don't think I'll go back to those 'glory' days LoL.
More seriously, if Apple does that, it's just the second nail (after the $3k price tag, if true) in the coffin. It would be a complete flop except as a devkit item.
I just don't understand the need for massive processing power on the headset itself. Why don't they simply let the iPhone do that heavy lifting and simply stream the results to the headset and stream any sensor data from the headset back to the phone? There may not be enough network bandwidth to stream 8K VR data, but VR is a niche market anyway. AR glasses using this approach could be as light as regular glasses.