Some battery tests on Switch show that the 20nm Tegra X1 based Switch runs at:
http://www.anandtech.com/show/11181/a-look-at-nintendo-switch-power-consumption/2
Docked: System consumes about 11 watts
Undocked: System consumes 8.9 watts at max brightness (so lets say 8 watts common usage, since most people don't play at brightness cranked to the max).
That means with a Tegra X2 you could be looking at theoretically
Docked: 5.5 watts consumption
Undocked: 4.4 watts consumption
Let say the LCD display consumes about 4 watts at high brightness ... that means to get docked performance with a Tegra X2 ... you consume 9.5 watts (5.5 + 4 watts for the LCD) ... that's almost the same as the current Switch uses in undocked mode.
So yeah lots of things would be possible with a Tegra X2.
I think you will see two new Switch models next year, with the current Switch model basically phased out. Nintendo will want a new model(s) anyway because usually the 2nd year of a console/handheld is when they really want sales to ramp up.
