It's NVIDIA gameworks involve plus other enhancements/features, and on that, recommending 1080Ti to community, is NVIDIA's an honest business, not surprisingly new. As they have done in past and still are doing, but there will be 4K texture, which would required a meaty graphics unit to handle it properly and smoothly, and to deliver at healthy FPS.
While I do have concern on the 170GB, and this is almost 200GB. Was reading somewhere on the hard disk space requirement, FF XV in 170GB space is 29 Skyrims and 3 GTA 5. Well, the official requirements are usually overstated, but looking at the features and inclusions of 4K texture might be the cause. I hope this ultra 4K texture pack will be optional.
The minimum requirement for 4K and 1080p would tell how well optimized this game will be.
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JANARIOO So your next upgrade would be a 1080Ti