Recently it was seemingly semi-confirmed, that Square Enix has completely restarted the development of Final Fantasy VII: Remake, and thrown out most of the work done by previous developer CyberConnect2. This, of course, means the schedule has been pushed back, but while one could easily expect a year or so of extra development time, the change might result in several years of extra time needed.
According to Destructoid, producer Yoshinori Kitase and development lead Naoki Hamaguchi discussed the potential release window for the game behind closed doors at the recently held 30th Anniversary event for the series and here they floated the idea of a potential release window... in 2023.
According to the transcript, Hamaguchi found the notion of the release window unacceptable, and so is working hard to finish the game sooner.
This has yet to be officially confirmed or denied by Square Enix, but it would seem that we at least shouldn't expect the game to release any time soon.