OK! SO THIS IS A THING...
I saw this image in several Youtube thumbnails, so I Googled to see if I could find a better quality image and I think from what I heard it was found during datamining the game, perhaps leftover data from a memory that was removed in game? Maybe it's not a memory, but a simple snapshot taken with the Sheikah Slate (I say this mainly because of how Zelda seems to be looking straight at the camera) Either way I really want to see what this memory was supposed to be...Link in his Tunic of the Wild doing some Tai Chi (or possibly whistling) and Zelda in her blue dress (I really need more Zelda in her Blue dress) who looks like she's photobombing Link...
Perhaps we could still see something relating to this from the upcoming DLC...
Looking at the background it looks to be taking place maybe on the Great Plateau near the Shrine of Resurrection...Looks like they could be directly outside the shrine's entrance...
Another thing I noticed but, unless it's simply placed off screen somewhere, it appears Link doesn't yet have the Master Sword here...
Quick Theory/Speculation time...
One thing that has me somewhat intrigued about the story or at least not covered by the story is that, while it's reasonable to assume Link acquired the Master Sword in Korok Forest in front of the Deku tree considering the Deku tree shows familiarity towards Link, we actually never see when or where he initially gets the blade, he just has it...we only see Zelda return the Sword to it's pedestal after Link goes down in the final memory, but never when Link actually pulls it...and I've been thinking it could be possible he retrieved the sword from elsewhere and Zelda simply brought it to Korok forest, and the one place I've been thinking was where the Rusted sword is located not too far from the Shrine of Resurrection....The Great Plateau is a relatively isolated area from the rest of Hyrule and it's closer to that of the Temple of Time which is a popular location for the Master Sword...after Link successfully pulls the sword from it's pedestal he is then given the Champion shirt from the Royal Family after being made the Hylian Champion and Zelda's appointed knight...and his tunic was then taken into the care of the Sheikah...