Who cares how thick it is, what matters it what does it weigh? Not seeing that information.
I'm just not sure that there is much of a market for it. It's fun to imagine though. Mobile Xeon, ECC memory, 32 or 64 GB DDR4-2400 RAM, RAID NVMe SSDs. Priced like a Mac Pro :)
It's funny you mention that. The nickname for the 17" MBP was 'the lunch tray'.