YOU ARE WRONG!
LG G2 is getting Android O (8.0) (LineageOS 15) ... it is confirmed:
see the whole list of devices:
http://www.lineageosrom.com/2017/03/los-15-list-of-devices-getting-lineage.html
http://www.cyanogenmods.org/lineage-os-15-rom-devices-list/
http://www.lineageosrom.com/2017/05/list-of-devices-getting-lineage-os-15--android-8.html
But as I remember this was posted way before LG G2 maintainer was banned from Lineage team, so who knows?