I believe they would follow the AEV beds which was built in conjunction with Jeep engineers to meet production standards. The reason AEV went that direction was to keep the truck light and not add extra wear to the driveline/suspension a extended the longevity of the vehicle.
Except if you still want trail capability. Jeeps go MANY places a "real" truck wouldn't dream about. The lengthening of the wheel base, even 20 inches for the scrambler, is going to hinder that performance.
I have never needed a 6'+ long bed nor would I want one. I like being able to park it...
I put stuff through my sliding rear window on my current truck. I'm sure a sliding window or removable glass will be an option.
I'm not sure if it would be cost effective but I would like to see it too.
I am a former Wrangler owner but currently own a Nissan Frontier (only because I needed a pickup). Based on the spy shots and mockups the JT will be nearly the same length with similar cab to bed proportions.
The two things that drew me to the Nissan was the Utilitrack system and bed...