I thought the same as @watsonyourbed. Maybe I’m to deep in this show’s hell, but to me, this shot of them fits just perfectly with the point in the johnlock arc that we are now. And rightly so, because they put that much effort to details.
This is how I read it: Sherlock is ready, staring at us, just waiting for John to catch up and take that one final step forward. John’s still looking to his left though, at something/someone (ahem, ‘Mary’) that makes him cross his arms in rejection/defense/anger; he’s staring at the reason why he’s delaying to take that step. Meanwhile though, John IS standing by Sherlock’s side nevertheless, because for him ‘it’s always (Sherlock’s) way’ -he loves him, duh.
Also, the overwhelming amount of blue here is just brilliant. Blue is the colour of trust, honesty, loyalty and stability. Some say ‘Blue is the helper, the rescuer, the friend in need. It is a giver, not a taker. It likes to build strong trusting relationships and becomes deeply hurt if that trust is betrayed.’ Also we all know that ‘feeling blue’ implies sadness/melancholy. And LISTEN TO THIS: blue relates to one-to-one communication, especially communication using the voice - speaking the truth through verbal self-expression. There’s a lot more to it, just google it, but- can’t y’ll SEE?! We’re in for an emotional roller coaster!
Oh, and I should also mention that when a character shows a change in hairstyle it is a BIG thing. We’ve all seen the amount of product in John’s hair, yes, but it’s interesting to mention a subtle dichotomy. While John’s new dramatic slicked-back hair leaves his forehead exposed, giving a sense of openess (the promise of coming out), his collar button is not undone just yet. Unlike Sherlock, who’s always been (openly gay) casual and carefree with up to three buttons undone! So, there you have it, John’s emotional struggle to come out (thus allowing himself to establish a romantic relationship with Sherlock) will be a theme this season.