So far, I've found two hints for what the next DLC might be. Both are open-ended statements that haven't been closed. So, spoilers from here on out:
The first is after the quest The Silver Shroud. If you successfully save Kent Connolly, he says that he has something in mind to do with the Sole Survivor, something that he's planning, and he goes back to the Memory Den. I'm thinking this is hinting at more Silver Shroud fun involving memories, but I'm not sure exactly what.
The second, and more exciting one (at least for me), comes after the quest The Secret of Cabot House. If Jack Cabot is still alive, and you go back a week later to get the Lorenzo's Artifact Gun, he says that he's uncerta