Nah OP. Even though it was a sloppy mess of a game FFXV sold very well. The 9 years or so it spent in the oven was kind of a mess too, imagine a small team doing preproduction for 4 years and then when they finally get the chance to build a proper game out of all that work it turns out the engine can't handle it. What do you do ? you quit after 2 years without ever ramping up to a full team. That was Versus XIII from 2006-2011. It wasn't "free" of course but it didn't cost 20 million a year either. I'd be amazed if they blew more then 20 million total until it was shelved in fact. PS4 devkits roll in and Tabata takes a look at what's there and says "I can turn this into a finished game in time for christmas 2014" so the higher ups let him. But by the time 2013 rolls around after a year of development it becomes apparent that the crystal toolset is still ass for what they want so they build a new engine from scratch. This takes all of 2013 and a good chunk of 2014. The game is now officially behind schedule by a year from it's new release date. Another 30 million was probably blown building it by the end of 2014. Work on a final release version begins AFTER the demo included with type 0 HD, this is the only time it gets a AAAA budget and 18 months of crunch I'm sure. I imagine this point in the games development cost another 50 milion. So add that all up and I don't think square spent more than 100 million on the games development from the Versus XIII days all the way through it's launch in 2016. All the DLC that ended up coming out might have represented another 15 million in development costs. It's marketing budget was quite large but I think all in all , even counting Kingsglaive in there, Square spent, AT MOST, 250 million on EVERYTHING to do with FFXV (outside of the mobile game). It sold 5 million copies almost immediately at full price, that's 300 million in revenue, of which square keeps close to 200 million. Since then another 5 million copies have sold for an average cost of about 50% the original sale price. 150 million more in revenue with 100 million going to square. Finally everything short of the mobile game (cross promos with other games, FF14 items and such leading to more subs, DLC, etc) probably lead to another 50 million or so in profits. So all the non mobile stuff at worst was still a return on investment, maybe not a HUGE one but a return none the less. The brand was profitable. It also re-ignited the brand as being a high quality franchise after some duds lowered that a bit. The mobile game does some sort of profit sharing nonsense and has generated enough cash to pay for FFXV twice over , even if square only gets a cut of that , it's still a lot of money.
So no OP, there's no way Square stops making "new" final fantasy games. A release date for one this coming generation might be tricky due to FF7R but , it will happen. It's production also shouldn't suffer from all the problems which plagued FFVsXIII/XV either.