
So beautiful
Since it seems that OP has deleted, and this was never posted with artist credit, the artist is toerning on DeviantArt. And this is part of a post-reichenbach series she did, which also includes this piece, this one, and also this one.
Though, the artist states you can interpret the piece as you wish, in the context of the series, I think it is clear that this is John dreaming/hallucinating Sherlock is actually there.
I don’t want to be pedantic, but this particular drawing isn’t part of the artist’s post Reichenbach series, @sussexbound-main. The title of the piece on deviantart is “A No Patch Kind Of Day
…which is as close to it gets to a lazy Sunday for Sherlock” [bolding mine].The artist’s statement about interpreting the drawing also isn’t related in any way to “Reichenbach” but to shipping Sherlock and John.
It goes as follows: “Feel free to interpret this drawing however you will (and many of you will,) but I don’t actually “ship” these guys […]”.So this piece can be interpreted in many ways. It could be a happy, as well as a sad scenario, it could be post Reichenbach, or not Reichenbach related at all.
However, someone apparently felt inspired and wrote a post Reichenbach fanfic for it. The link to the story on the deviantart page is broken, but it’s called “Far from my Gaze“ and
can be found here.
In this story, John doesn’t hallucinate Sherlock, but Sherlock actually visits 221b secretly while John is asleep.