Cache thumbnails relative to file locations

Could the thumbnail cache have an new option to support storing the thumbnails relative to the location of the image files?

I have a lot of photos both personal and for clients that are stored on network drives and also USB backups.
Ideally I would like the thumbnails to travel with the images. So if I open the USB drive on another PC the thumbs are already calculated. As well as not taking up space on my machine when not using the drive.