You can still accept OTA official update on rooted G2 as long as you don't have a custom recovery. You'll just probably lose root after update. There's a survival mode in SuperSU for keeping root, but I'm not sure how well it works. If you end up rooting and need to send it in for warranty service you can use SuperSU to unroot. Then go in download mode to verify it's unrooted. Worked without any issues when I had to send LG my G2 after started having LCD issues.
Sent from my LG G2 running SlimKat