Luminous Studio staff hint another FF besides XV is already being developed for next-gen.

[teigaga]

Could be a good or bad sign.

Good If this means they are already working on FFXVI, obviously a separate team. It harkens back to the Golden era where the main entries were'nt seperated by 5 years with rubbish spin-off and sequels filling in the gaps inbetween

Bad if it means they're working on some unwanted/uneeded spinoff.

Although based on the intended use of Luminous engine, this could be anything ranging from Tomb Raider Next gen, to a 3DS or PSVita game.