Am a big fan of 12 because of Bunny Fran's PLOT lol. On a more serious note I do like 12's battle System. Dragon Age's Battle System was inspired by 12 too said Bioware. 12, 13 and 15 still have the determining battle system elements of a mainline FF game. 12 got an HD remastered version with many improvements on the battle system because of the complaints from the original ff12 game so that factored in on people coming around on 12 I think. The recent spin off FF game, stranger of paradise's battle system is more mainline FF like, than FF 16. If FF 17 is another fail and in 10 years many of the older fans that do not like FF 16 are dead or no longer active in gaming and the ones that like it are still alive and active then it's possible for it to happen with ff 16, hearing/reading more people liking Ff 16 and/or coming around on it. But then it's not a "real enough" general consensus' opinion of the game imo. Now with FF 7 Rebirth and FF 7 Remake, the 2 games battle systems are awesome. Even with gamers that hate the new story elements of Remake and Rebirth, majority still like the battle system and said still mainline FF like. FF 17's battle system should at the very least like Rebirth.
Sales wise FF 16 needs frequent price drop to sell, 16 rarely hits the top 10 spot ps5 games on amazon months after release even with discounts, Rebirth still hits the top ten spot on amazon from time to time months after release and in the top 10 most wished game list on amazon from time to time. On PC FF 16 when it was on preorder it's on the 32-40 spot steam best selling single player game list while rebirth hit the no 1 spot steam best selling single player game list when the pre order was announced. With ff9, 12, 13 and 15 at least the sales of the game were still much better than ff 16 during the release time frame. Also you had Yoshi-P suddenly said the 18 months sales plan when the preorder of the game was bad on PS5. They guy has a rather big ego and he wouldn't say that if the pre order was great. So if SE is smart then they should make the next game more like the classic ones rather than something like FF 16 imo.