I'm going with this one not suffering a switch of console and restart of development like FFvsXII. It seems the general track record is that between announcing a single player main numbered title and releasing the game, since FFXII it's been 7/6/5 years (or 11 if you count FFXV since the start of FFvsXIII). So, I'd say that we're looking down at least 3 years post announcement. It's 2020, so 2023 seems the earliest option unless they learned something from the XIII sequels and/or WoFF that will allow them to speed up the process. Sadly I'm not that confident. People are saying that it looks like it's further along the development, but presonally I don't put much weight in a trailer. They even admitted about FFXV that they had a trailer out before they had any form of playable game, if I recall correctly.