A lot of people, myself included, are worried that the joycons are going to be too small.
A lot of people, myself included, are also concerned about the battery life.
So what if they release big joycons that include big honkin battieries that extend the life of the system when portable?
Obvious issues would be the price. If people are complaining about $80 dollar accessories now, imagine the cost with a significant battery in it. Also the system would already need to be designed to charge upstream from the joycons, which it may not. Still, a nice idea.