Place a mirror opposing your monitor, place your keyboard and mouse in front/at-an-angle to the mirror, and turn your computer chair around.. do it Legend of Zelda style and flip the entire world!... voila!
It would be neat to see maybe a specific archetype (or two) be a southpaw. I don't think mirroring animations would be a high enough priority feature in a crowdfunded game like Crowfall. They'll likely want to squeeze as much time and effort into the bigger picture stuff. However, I think it would be completely plausible to have an archetype built from the ground up being left-handed, unless there is some specific hit-box/collision constraint.
On the left-hand input side-topic, I really hope Crowfall has a robust/editable keybinding system.