In an interview with Rock, Paper Shotgun, Tim Schafer reiterates his desire to eventually make Psychonauts 2 (and maybe I'm too sanguine, but at this point I feel like that one's just a matter of time), but also spares some optimism for a continuation of Double Fine's heavy metal saga:
Make no mistake, however: Double Fine still very much wants to make a Brutal Legend 2. But, as with Psychonauts 2, it’s a matter of waiting for the planets to align on a scale that even prog rock album covers couldn’t dream up. Then again, this is Double Fine we’re talking about. The same Double Fine that kicked off gaming’s obsession with Kickstarter and recently managed to sell a game jam. Crazier things have happened.
“I mean, it’s been longer since Psychonauts and we wouldn’t have to do any music licensing,” Schafer pointed out. “So we could probably afford to do it more if we got some funding. I feel like a Brutal sequel would cost twice as much as Psychonauts. It’s easier to imagine Double Fine doing a sequel to Psychonauts. But for creative reasons, there’s no preference of one over the other.”
Either way, Double Fine apparently has ambitions to expand the original game with more downloadable content - for the multiplayer campaign, anyway. From small enhancements to entire factions, the studio was forced to cut a number of features from the game that they could resurrect if the PC release proves successful enough. Recall that the company had even begun work on a full-fledged sequel before EA was all like, "Psyche!" - one imagines that there's a ton of vaulted ideas for Eddie Riggs' future just waiting for the disinfecting sunlight of capital investment.
Source: Rock, Paper Shotgun