Since you established that all the worlds you created in your books are linked, any chance to see in the (very) distant future a book/series that delves into this overarching story/universe/rules more directly? Possibly with a crossover of characters from your different stories, specifically characters that became "immortal" or at least achieve a "different" state: Sazed, Kelsier, Raoden. Is that something you would even be interested in doing?
Or will you stick to placing subtle hints in your different books/series about the overall system?
VERY distant future is correct. I will confirm that I do have stories planned that delve into what is going on behind the scenes. There will be short stories dealing with Hoid, most likely posted to my website.
Some of these stories are novel length, and I can't say what I'll do with them. Perhaps I'll write them out in novel form and release them in bookstores, but I have a feeling that most of my readers would be completely confused by them. So perhaps these will all just be on my website only. (If they are released that way, they'll most likely be free for download and reading.)
The subtle hints will continue until then. Mostly, I want the stories to be enjoyable and self-contained. I don't want anyone to HAVE to know any of the behind the scenes, regarding Hoid, Adonalsium, and the rest. (Yes, there is more.) Those are there for the readers who want to dig, and who want to see the greater story. But I don't want them to overshadow the stories of the books themselves. At least not yet.