In an interview with Dream Team FC (Link), EA explains that FIFA 18 uses a custom engine based on FIFA 16’s “ignite’ code, and for good reason.
“We intentionally chose to do a custom engine because we felt that rather and try and get Frostbite running and end up having to downsize things and making it just a smaller, lower-quality version of the PS4 and Xbox One versions, we wanted this to be a FIFA that stands on its own two feet.
“We want people to recognise it and play it for what it is rather than saying, hey, you’re getting a sh***y, second-rate game. This is a full FIFA that players players (sic) will enjoy.”
Though EA has previously claimed that the Nintendo Switch is capable of handling the Frostbite engine, it seems that it might not be as efficient as it could have been on the Switch.
Despite all these, EA confirms that the game will still look good, pushing a full 1080P 60FPS when docked.
FIFA 18 for the Nintendo Switch launches on 29 September 2017.