They won't do fixed controllers, I don't think, since the whole point of the switch is the versatility and the joycons.
Unless switch fails miserably, then maybe, but then you disable certain portions of the library, which would be bad.
I suspect the switch will get hardware revisions, just like every nintendo portable has had, but I also suspect they'll all support joycons and the dock, as well. Possibly even a vita-tv-esque device, but even that would still have the joycons.
They can always make a smaller or a larger revision as well, with different joycon sizes to accomodate (switch mini with mini joycons).