It's now possible to change the depth of field after taking the photo. I wasn't paying close enough attention to know if this will also be possible on older iPhones. EDIT: sounds like it's just the new iPhones. But it includes the less expensive Xr.
I don't think it was mentioned in the keynote, and I hope it isn't just a software flag like what they did with Live Photos on the iPhone 6S:
https://www.theverge.com/2015/10/15/9546639/3d-touch-live-ph...