There's a thing I realised only now...
It has been said before that in this shot John and Mycroft look like the two angels on Sherlock's shoulders. Nothing new there.
What only struck me now is... What kind of angels are they? To the left we have the "Caring is not an advantage"-angel. To the right the "Romantic entanglement would complete you as a human being"-angel. They're representing the two contrary options of how to deal with his emotions, or more clearly with love.
And Eurus' goal with this task is neither to hurt Sherlock with the cruel treatment of Molly, nor the "I love you" now lost to be first said to John.
But rather, by forcing Sherlock to hear these words, which are the epitome of romantic entanglement, without them leading to the completion he was promised and to say them himself in return without meaning them, to the one person he knows who would actually want nothing more than that, and by doing so knowingly cruelly hurt someone he actually deeply cares for and therefore at the same time also hurting himself is so sickeningly twisted that it contradicts everything in itself. It destroys all the intentions of his "angels" and turns both options his angels offer him to take care of his heart into a dead end.
She took every option from him to take care of his heart. Which makes the following breakdown even more painful.
Which made me realise something else:
Exactly John... somebody who loves somebody.
The discussions were going strong if this coffin was for John or Molly or both considering they're mirrors, but... I realised... the plate on the coffin...
Usually, such a sign placed on the coffin is not a message left behind for the bereaved by the person who died. Actually, it is much more likely to be a last tribute and love declaration to the person who passed away, sent to the grave with them by the person who loved them most.
This would mean Mycroft might be wrong. This coffin isn't for someone who loves Sherlock Holmes. But maybe rather the opposite: for someone Sherlock Holmes loves. Or even more, in terms of metaphors: it's for Sherlock Holmes' love.
Euros tries to bury Sherlock's love. He even seals it by putting the lid on the coffin. His "angels" leave, nothing left to say.
The rather hopeful ending though: Sherlock destroys the coffin, his emotions too strong. He's not letting Eurus win!
(little side note: zooming out of that scene we're even leaving Sherrinford for a moment, looking at it from the outside, rain[=emotions] pouring down)
And afterwards? Who's returning and helping him up to carry on? His "romantic entanglement"-angel! While the other lurks defeated in the background.
That's saying rather a lot, I think.
