The main problem with the theory is the basic idea that if you cut out the dock that somehow you save a ton of money thus allowing a "Switch Portable" to be much cheaper. It would be basically the same price.
Especially at the rate Nintendo will be mass producing the docks (several million per year for the standard model), they'll likely be getting them for like $10 or less a pop. It's just an HDMI pass through and some rudimentary hardware with two USB ports.
Dropping the dock and batteries in Joycons saves you maybe $20. So your system is $230 instead of $250. Whoopity doo, I'd rather pay the extra $20 even if I rarely used the TV feature + Joycons. Also I would bet dollars to donughts, custom Joycons are definitely coming.
GameCube Joycon. Kirby Trackball Joycon for Kirby game. Special Pokemon Joycons. Etc. etc. etc. It's going to be a central part of the NS concept I bet. You will be locked out of this functionality with such a model.
Nintendo could offer it, but I think it would amount to niche sales, kind of like a crappier selling 2DS.
