Re-organizing images

I am working on a site for someone and they declined to organize images by date. Don’t ask me why.

Now they want them by date.

So I figure- export the xml, find and replace with correct paths, sort images by date and put them in the right folders.

However the featured image is noted by an id not an image path. So will I lose all featured images? And, will this cause duplicates in the media library- with one of them broken?

Is there an easier way to do this or am I staring at a brick wall?