I was thinking the hair was way too short to be Kasumi, but I checked the original trailer again that shows Leona, and her hair is actually noticeably longer. Plus this teaser doesn't seem to be wearing those thick gloves Leona has.
Then again they clearly turned everything smooth in that teaser image again so whatever. I'm assuming it's Leona because she was in the trailer but they could reveal this teaser to be Choi and I wouldn't bat an eye at this point.
If I struggled to the end of my determination, to the end of my way of life with my followers, if the result is ruin, then this ruin is inevitable. Grieve. Shed tears. But you cannot regret.