Rumored 12 inch MacBook - No USB ports due to size constraints?
"The offering will likely be lighter and slimmer than the existing MacBook Air to further highlight ease of portability in the cloud computing era." Link
The size constraint on the current MacBook is the height of the ports (USB to be specific). So if it is to be thinner, wouldn't Apple need to remove them? I think it's possible as you have bluetooth for peripherals, cloud storage for external drives, etc.
The only ports I that I think would remain would be a headphone jack, and possibly a SD card reader (as it is fairly thin and the only way to get photos off a DSLR and onto the laptop if it doesn't have USB).
Add cellular connectivity and I think you have a "forward thinking" next-gen laptop.
But perhaps it's too soon for USB to go the way of optical drives and disk storage...