When I was looking into this, I found out that it’s a 22 floor of building she fell from (Jason is at 26th floor) and realistically, I don’t think anyone would survive a fall from that height. Even if they did survive, they’d likely be  paralysed and end up in coma.

Then there’s Carl’s message at the end of the extended look, telling Jason to “enjoy the present.” It just gives me a feeling that a major tragedy is going to happen, and that this mission could mark the end of one of the game’s chapters. This could be the point where the game actually starts getting intense, moving beyond simple shop robberies and working for others, and into bigger, more personal missions, maybe even setting Jason on a path of revenge.

Rockstar also wouldn’t necessarily shy away from killing one of its playable characters if it served the story.  
I might be stretching a little here, but could there be a possibility that Jason changes after this tragedy? In one of the screenshots IGN provided, where Jason is up against a fence alone with the police behind him, he looks pretty sad, and there is a picture with jason bit rough and angry with grown beard.  I think these two screenshots are the only two images where we can see such intense emotions in his face.

Could This Be the Tragedy That Changes Jason’s Story