There are something like 65,000 messages with photobucket links.
It is possible to automate a process for relocating photobucket images and re-hosting them, but making changes of that magnitude is tricky and a lot of work. Another way to do it, and one which would focus the effort on the most significant message threads would be for people to replace images when they are encountered. It probably requires a paid photobucket account or, maybe, one of the browser plugins if they still work. Although you can’t edit the original message, adding a message to the thread with the images attached would make it less of an effort for a moderator to go back later and fix the images in the original message.