Joycon != Pro Controller
It's interesting that they fixed it via a system update and not via a firmware upgrade for the joy cons.
Edit: looks like they provided a new firmware for the Joycons in the system update. But Joycons don't update automatically, do they?
So it's clear why they bothered to also add new firmware to the Joy-Cons: to try to fix the majority of drift problems.
Seems like system update fixes some Pro Controller drift problems, and the firmware included in the update does it for the Joy-Cons.
I don't know how Joy-Con's firmware update work, but I suppose their firmware will update itself when first using them after the system update installs into the console.
And, if that it's correct, the Joy-Cons of the SW Lite will also update this way, or even they'll update the same instant the system update is installed.
In any case, it is good news. I bet they worked out the fix thanks to the discovery of the trick done in the video I posted in OP. In the comments, there are many people reporting they even succesfully fixed their Joy-Cons after applying the trick. I'm sure those who fixed the problem with the trick or the update thought their Joy-Cons were
hardware-fucked. But there you go, I also bet at least 50% of drifted Joy-Cons are now solved by the trick or the update.
But, IMO, there's only one more thing needed: a system update which ables the user to configure deadzones for the Joysticks both in center and every axis' furthest point.