I don't think we'll see DX12 implementation any time in the future. Maybe many years down the road and if SE updates the textures of FFXIV or not. Currently I don't think this game is looking dated at all in comparison to other MMORPG's in the market. It has its own art style and aesthetic design choices that make it unique to say something like ESO or Guild Wars 2 and colors are bright and vibrant and pop out quite nicely. I don't think FFXIV is going to age as poorly as FFXI did in the visual department.