This might be a relatively short post.
After the release of the BBC Original Drama Autumn Trailer, lots of fangirls and probably some fanboys too got very excited at seeing Sherlock & John back in action. In fact, the top voted comment at the time of writing this has the words "JOHNLOCK" and "gay" in it. I'm not a fan of the 'shipping' of two characters who clearly aren't gay, because people start watching it for Tumblr Gifs, and not for the actual drama.
When the first Sherlock trailer came out, there were similar comments. Sherlock's face when he sees John, which to me looked slightly constipated, was caught on by all of the fans in an "omg his face, this will be so sad" kind of way. I mean, Sherlock's face didn't attractive quite as much attention as John's moustache - but hey ho.
My point is, the arrival of the new trailer brings about/shows two things. The first is mentioned above - the shipping - which is one thing Sherlock shouldn't do. That will never happen though, so that's not a worry of mine, just an annoyance.
The other thing the trailer showed was that the plot looks to be as predictable as I thought - and that's what Sherlock shouldn't do. The trailer features him and Martin Freeman's wife/John Watson's (we presume) Mary riding a motorbike. Despite this being done, in the same location, in Doctor Who failure The Bells of Saint John. But aside from this - it highlights what's present in the filming pictures.
Now I may be wrong and I'm sure the story will be more complicated than this because it's Sherlock.
But I'm pretty sure the base of the story will be "Sherlock comes back/John hates him/John hits him/John's girlfriend forgives Sherlock/John and girlfriend argue/Sherlock and Mary save the world/John forgives him". Along there there'll also be the "us two against the world" line that was in the trailer - something else that excited the Tumblr fans.
That will be the basic plot. The underlying tension. Hopefully it won't take the whole episode for Martin Freeman to stop breathing heavily in anger, but it might do. Hopefully - that plot won't happen at all.
Because it shouldn't. I could make up that plot in my sleep - in fact, people younger than me who watch enough TV could make that plot up in their sleep. So yes, the plot around it about "The Empty Hearse" will be very good I'm sure - but it stands a chance of being ruined by John's annoyance. The arguing/falling out/getting back together/saving the world has been done SO MANY TIMES and I really hope I'm wrong. I hope the clips from trailers and filming are misleading, and that the most predictable TV character plot in history hasn't been chosen to bring Sherlock back.
It's definitely something Sherlock shouldn't do.