Bang for Buck also has a video of BFV using over 9gb,
https://www.youtube.com/watch?v=BpetTcK4Vgk
Personally I wouldn't buy a card with less than 11-12GB ram if buying now. The 1080 Ti /Pascal XP have been out for over two years and future games will only get more demanding. Sure you can dial down settings but buying a card costing that much only to be VRAM limited sometime soon doesn't seem wise. 1440P should be OK for a while as that's at 4K but if it was me I wouldn't compromise on VRAM. I remember my 6990 becoming RAM limited before it was GPU limited and that was annoying. Games out now need more than 8GB so I can't see there's any 'future proofing' in buying an 8GB card for todays and tomorrow's games.