A user on NeoGAF has made quite an interesting discovery. This particular user claims he found a new trademark registered by Remedy Entertainment called "Alan Wake's Return" registered on February 23rd, 2016. This is monumental news for the cult classic, Alan Wake.
Although, this isn't an announcement of a sequel (Alan Wake's American Nightmare excluded), it's worth noting that in the DLC for the original Alan Wake entitled "The Writer", Alan Wake writes a book named "Return."
A sequel to Alan Wake has never been out of the question. In fact, the creative director at Remedy Entertainment, Sam Lake, had this to say about a potential sequel in April 2015:
"For Alan Wake, from the get-go, we assumed there was going to be a sequel and we mapped things further out when it came to character, story, details and focus changes," said Lake. "We knew we would have to iterate and refine, but there was always a rough road map there.“
Stay tuned as the story develops further...