I'm not against the idea, but I wouldn't want one for myself.
As has been pointed out, the Joycons will have to remain attachable to the outside of the clamshell.
Both DS Lite and 3DS had widespread problems relating to the clamshell. The DS Lite had very fragile hinges, even a small drop off a coffee table could cause it to break. While the 3DS had improved hinges, they still had problems - wear and tear over time causes the hinges to loosen. The big issue with 3DS was the bottom screen biting into the top screen. So Nintendo really would have to make sure they get the design right with the Switch because Switches are much more expensive devices.
But the question from a company standpoint: What business and creative goals do a clamshell Switch contribute to?
I describe myself as a little dose of toxic masculinity.
