Nintendo already stated a firmware update is coming last week.
They adding:
* Chinese
* Korean
For system languages and for Online they are:
* Renaming the eShop to Nintendo Switch Online Shop - No more Nintendo WiiU it shutsdown at end of month
* Expanding the online regions with many more areas added including of course China and South Korean.
For other changes, we don't know yet, as 'system stability' could be nothing at all, but its best to play it safe.
At 5:50pm Pacific time the Online network is going down, and when it returns at 8pm the firmware should be live.
For Nintendo it is two day job, so if they do not release the firmware tonight, they will do so tomorrow, they also shutting down Online network again tomorrow during the same hours.
Finally on Wed. night after 9pm they are removing all the Wii U stuff, so if you need something there, grab it now before it goes away forever!
Gary could you please if you're posting about sth like that also add this updates to main post... I know that always is good to read more pages than main... but good practice is add edits and updates as developers do, because about this info better is first read main thread and second to read last few pages or more. I am posting because you have better knowledge or info maybe from TX or sth els.
Thanks