On a Destiny-VIII website Square Enix appars to have created a place holder site, for an upcoming new cross-over title, which could be the very first of its kind.
Square Enix appears to be suggesting that the Final Fantasy Studio, which is meanwhile creator of mobile games as well as PC and console games, is working a new title. The most interesting part is that it could be the first true cross-over game to hit the market. Other than that the name of the new title must be Destiny VIII.
On the 8th of January we're about to learn more about this upcoming game. We're actually quite curious to see the first teaser trailers and some more in-depth information on this games, since the concept of cross-overs sounds rather interesting to us.
Source:
Destiny-VIII