I don't know, Bethesda openly says that Fallout 3's DLC cycle was exhausting and kind of unfulfilling for them. That's exactly why they went with a quality-over-quantity approach to Skyrim's DLC in the first place. And I feel like Skyrim's DLC was more commercially and critically successful, too, although I couldn't confirm that. Personally, I think Beth really hit their stride with Skyrim's DLC, and I'd love to see them keep that up for Fallout 4's DLC.
New Vegas handled the multiple DLCs really well, but a lot of that seems to be because Obsidian planned ahead for them. New Vegas's DLC is better than the main game; if Beth can do that, I'm still down for it, but I think we'll see DLC similar to what Skyrim did. They didn't plan the DLC much during development, so a lot of the design for Skyrim's DLC took initial feedback from the base game into account; lots of improvements to mechanics people were underwhelmed by (vampirism, lycanthropy, mounted combat), dungeon puzzles that were actually challenging, etc.