Great news, this I think is Nvidia adding HDMI-VRR to the G-Sync compatible branding (like they did with Freesync displays) though that remains to be seen until it's released.
Also keep in mind Nvidia are saying only the RTX 20xx series cards are getting this support, these cards are HDMI 2.0 ports only as well.
What that means is LG's G-Sync range is 40-120hz but for HDMI 2.0 ports that will top out as 1440p@120Hz to use the maximum range.
If your at 4K@60Hz over HDMI 2.0 then the likely range will be 40-60hz, still useful if targeting 60fps frame rates.
To get 40-120hz at 4K@120hz needs a HDMI 2.1 port of which there are none on the PG GPU market currently.
Now if LG could only add PCM 5.1 support to their eARC that would perfect the 2019 OLED's for PC gaming.
As a Nvidia 2080Ti owner with an LG C9 this is amazing news! I play at 4k, and though it's a powerful GPU, some games like Shadow of Tomb Raider hit more like 50fps on ultra settings.
If they added DisplayPort 1.4 to the TV that would overcome the limitations of HDMI 2.0. Don't think they'd do that though.
It's a superb move by LG and has pushed their TVs to the front of my list for next TVs whenever that is. Hopefully others follow suit too.
Wrote this in the c9 thread and thought it might be interesting here aswell:
Looking like g sync support is coming already this october! Hope we are getting it the next week or two. by the way, the g sync range for 1440p is 40-120hz according to the nvidia article below. Guessing 40-60 for 4k due to GPU hdmi 2.0 transfer speed limitations.