It's unlikely to be anything but a tweaked Tegra X1 based on power constraints alone. Since we know pretty well the battery life and its mliliamp-hours, we can more or less estimate the watt-hours, since Wh = mAh x V / 1000.
4310 mAh * very likely 5V / 1000 = 21.55 Wh, which sounds about in line with other tablets.
Theoretically, it can last at least 2.5 hours on demanding gameplay, so that's 8.62W, a very high power consumption for a tablet, but not unusual for the Tegra X1. According to Nvidia itself (https://blogs.nvidia.com/blog/2015/01/04/live-nvidia-ces/) , the Tegra X1 runs the demanding Unreal Engine Elemental demo on 10W. That would be a close match to the power consumption of the Switch hardware, when being stressed.
It sort of implies, though, the hardware can run close to full speed as a handheld, unlike what the Eurogamer rumour says... of course, one must remember the Switch could still be limited by heat; and there is a good chance the Nvidia benchmark might be excluding the power consumption of the remainder of the system (mostly the screen) from the 10W results it claims.
