https://press.na.square-enix.com/releases/1142/lara-croft-arrives-on-final-fantasy-brave-exvius

The official Square Enix press release about the Lara Croft collaboration has this bit near the bottom:

Several new updates will be added to the game during the collaboration event as well. Beginning March 6, new players can acquire the 5* max Level Ashe (FINAL FANTASY XII) from the tutorial gacha, pick up 5* Lightning (FINAL FANTASY XIII) as a reward through the Rookie Mission and more.

Presumably veteran players won't see any kind of tutorial gacha, but if it's a new rookie quest, it's likely we'll all be able to get a free Lightning. It's something!

Edit - u/elytraxp noticed that the press release has updated, changing the date to March 8th instead of March 6th. Which, of course, lines up with our normal update day.