Please bring out actual facts with links that back up your claim instead of making random assumptions about dev costs. The game wasn't even in full production until late 2011 and then was rebooted in 2013 so they lost what? a little over 1 year of dev costs. So your claim of 'years of development' doesn't even make any sense. It had the same development cycle as a typical AAA game from 2013 to 2016.
The project that became FFXV began production in 2006.
You can split hairs about "full production" all you want, there had been significant amounts of work done on that project before it was rebranded, and significant amounts of work done under Tabata built on top of that existing work when he came aboard to salvage it.
I mean, I don't even know what you're arguing - that for 6 years it was just Nomura sat at a cubicle by himself doing sketches and rough plot beats with no other staff? Come on.
It can still be successful without living up to their expectations for the franchise.
Do you believe that SE are 100% satisfied with how it has performed at market as their premier franchise?
Do you believe that they consider FFXVs development an exemplar for how to develop a modern AAA titles, and they will do everything they did with it over again in their next project because it was such a trouble free project that was so stress free and enjoyable to work on?
It was a troubled project that they successfully brought to market, that in no way diminishes that that is an achievement in and of itself but - again -
my impression is that they wanted more that it achieved, and will continue to produce spin offs reusing assets because those can contribute to what they want the franchise to be, and can be made cheaply on top of those already sunk costs.
Generally speaking, companies make decisions on how to optimize growth and profits for the future, as opposed to looking at individual sunk costs in a vacuum and trying to make those look positive.
This is why, for example, companies cancel games, even though they'll never make money back on the stuff they made for the game that got canceled.
Yes, but they learn from those sunk costs; their company wide movement towards middleware engines and away from developing their own engines for example is almost certainly as a result of things they learnt during FFXVs troubled development and their collaboration with Silicon Studio.