From a commercial point of view a cheaper "only docked" version would probably backfire. It would only make the regular switch look more expensive a less convenient, thus making pressure for Nintendo to lower the price. At the same the "only TV" model should still cost less since it lacks the main feature of portability. In the end it would only be a vicious cycle.
Imo, an "only TV" model could have more chances to work if priced the same as the regular Switch. In that case it should offer better graphical quality to compensate the loss of portability (higher resolution and the likes).