Recently game director for Final Fantasy XV, Hajime Tabata, teased the release of Final Fantasy on the Nintendo Switch during a live-stream. A lot of people picked up on the news and were curious about what that could mean for Switch owners. Well, Tabata clarified that you probably won't be seeing Final Fantasy XV on the Nintendo Switch anytime soon.
Speaking with DualShockers, Tabata-san explained that when the team tested the Luminous Engine (the design suite used to build Final Fantasy XV) on the Switch, the results weren't very positive. The team wanted to make sure that if it runs on a platform that it makes the engine really pop (which is understandable, since it's an internal proprietary engine that Square owns, similar to Konami and the Fox Engine, and EA and the Frostbite).
The one thing that the team did not want to do is waste an opportunity by quickly doing a port job for the Switch, so Square is now investigating further about putting Final Fantasy XV on the Switch. Preliminary tests also showed that the Switch had no problems running prima facie optimizations for the game through Unity and Unreal Engine 4, but there weren't any dedicated resources put into optimizing the Luminous Engine specifically for the Switch.
So it sounds like if Final Fantasy XV is going to be ported to the Switch and run on the Luminous Engine then there will have to be a lot of proper scaling and optimizations made.
This isn't to say that the game may not ever come to the Switch, but it's not as simple as just taking the game from one console and putting it on another.
Also, keep in mind that while the Switch could easily run Final Fantasy XV in docked mode at maybe a lower resolution (or possibly through dynamic resolution) at around 30fps, the problem comes in with the game running in the portable mode, where it will lose more than half of the GPU processing power. It's something that could pose a serious problem for a lot of AAA games coming to the Switch.
The lowest common denominator for the platform isn't its highest spec output but its lowest, which would be the portable mode. So a lot of developers definitely have to take this into consideration when making games for the console.
So this doesn't really say anything about the possibility of the game coming to the Switch, only that it would definitely require more effort and so it won't be a quick port job. Then again, the PC version of Final Fantasy XV took two years to port, and high-end PCs scale far above the capabilities of the Xbox One and PS4. So even then it still required Tabata and the crew a good deal of time to optimize the Luminous Engine for the PC version of the game, which is due out in 2018.
Some gamers are hoping maybe Square will use a completely different rendering platform, possibly taking the mobile version of Final Fantasy XV and upscaling it to take advantage of the Switch's unique rendering capabilities, similar to what Nintendo used for The Legend of Zelda: Breath of the Wild, or what Ubisoft used for Mario + Rabbids: Kingdom Battle. For now, though, you'll have to sit back and wait for more details about what plans Square has for Final Fantasy XV on the Switch.