The total price of ownership.
If I get a Switch, it will be as a secondary system, so I'm not that concerned about things like multi-platform releases. I'm also fully anticipating it eventually building up a good library of the 3DS RPG type games I'm looking for. I don't care much about most of Nintendo's home console type games, especially platformers.
Basically, what I want is something like 3DS third-party content but on a home console. The handheld portion means very little to me. I'd definitely want a Pro controller, though, which makes the price jump.
As it stands, it's just way too steep for me for something that I wouldn't play all that often. I really don't see myself getting one until A) the library builds up, and B) the price drops by a significant amount, possibly over Black Friday, which is how I got my Vita.
Otherwise, I'm pleased that games only seen on handhelds previously might make their way to a larger screen. I've tried handhelds and they are not for me.