Based on the videos of QC's gameplay we've seen so far, I made a config that looks close/very close to what will prolly be the lowest GFX settings of QC.

Made by guessing it won't be possible to hard-tweak the config file(s) etc, but only lowering the GFX at the ingame menu(s), just like in Overwatch or any (relatively) recent AAA games.

You can get it from there :
http://pastebin.com/Lbv1D2mf

Screenshots :
http://imgur.com/a/1dEkl