Considering the original gameshell has the alternative back with the GPIO slot, light key mounts and Lego brick interface, I’m “hoping” they would have alternate covers with both provisions for expansion, and a clean cut look.
Re: the fans, an intake and and output a lot must exist somewhere for proper air flow. It’s hard to see where it is on the devterm. Perhaps this is just an early render with less detail for certain things such as this.
The printer, while cool, isn’t something you would want permanently attached. If a GPIO is more your thing, I’d bet that making an alternate breakout board would be possible; mounted on the expansion port’s slot.