Earlier quoted context omitted.
Yah, you're right. Quoting from the review: "we’ve yet to find a battery / cable that can charge the console faster than it drains." So it's possible and likely that someone will make a capable pack at some point.
Looks like it won't take much. A lot of USB-C power banks on Amazon max out at 3A/5V; at 15W, that's just about the top power consumption measured on the Switch (16W), so it ought to be enough to at least keep the battery constant as power use fluctuates during regular gameplay. I expect we'll see 5A+ power packs in the future which will handle it easily.
It charges my XPS 9350 just fine, so it should do the Switch no worries.