Wizards of the Coast operates like any other company: It has to register patents and trademarks for the ideas it comes up with before it produces them in reality. And since this is public knowledge through the US Patent Office, any enterprising Magic fan can stumble upon a name that Wizards has trademarked (although it's impossible to be sure whether it's for Magic, Dungeons and Dragons, or some other product). What I'm driving at here is: MTGSalvation rumor mill user Chinface found documentation that Wizards has trademarked the name Journey into Nyx.
The relevant text from the application, accessible on uspto.gov, is this:
Word Mark JOURNEY INTO NYX
Goods and Services IC 028. US 022 023 038 050. G & S: Card games, trading card games, playing cards, and accessories for use therewith
IC 041. US 100 101 107. G & S: Entertainment services, namely, providing online computer games and interactive multiplayer online computer games via a global network; providing online publications in the nature of e-books in the field of fantasy adventures
Filing Date January 22, 2013
Current Basis 1B
Original Filing Basis 1B
Owner (APPLICANT) Wizards of the Coast LLC LIMITED LIABILITY COMPANY DELAWARE 1027 Newport Avenue Pawtucket RHODE ISLAND 02862
This is a relatively new application - just filed at the end of last month - so it's seriously doubtful that it'll be the name of the first set in "Friends" block, or even one of the following two. It's possible, however, that this is the name of the fall 2014 large set. "Nyx" is, as is pointed out on the MTGSalvation thread, the name of a Dungeons and Dragons deity. However, the way it's used in this name seems to imply a place, and the "Goods and Services" section of the application lists only card games, not anything related to tabletop RPGs. This could technically apply to Kaijudo just as well as to Magic, but it goes on to list "interactive multiplayer online computer games" (as in Magic Online) and "online publications in the nature of e-books in the field of fantasy adventures," something that's produced for Magic but not for Kaijudo.
This could be a momentous discovery if it does indeed apply to Magic. The details are still fuzzy, but the information we do have points towards this being the name of a future Magic set!