The scene after the credits all but confirms that Moriarty also survived by faking his own death.

I want this to be true even if its a bit meh taken in a vacuum. Andrew Scott was a big part of what made the first two seasons great, he completely owned the Reichenbach Falls ep, so revealing that he also faked his own death somehow, was near death for a few months then by the time he got back on his feet found Sherlock decimating his network so he just decided to stay dead until Sherlock was about to fall is overall great for the show.

I dont know if they planned his return from the start, they have sort of said in interviews even before this season started filming that it was possible he faked his death too because he knew Sherlock would force him to do so, but how much of that was trying to just add to the lore and how much was real I have no clue.

But ultimately Sherlock should be him vs Moriarty and if nothing else it will insta get us back to where the show was great. I think knowing that Moriarty is coming back is what frames the death of Magnussen as perfect - he was devious, he was smart but he just wasnt on the level as Sherlock. The only two who should be on his level are Moriarty and Mycroft. Magnussen through information was power, Sherlock showed that nothing beats a 9mm at close range (except when you are Moriarty, somehow).

Ehh, not totally true. The writers could just be doing a breaking the 4th wall type thing. And I do remember seeing an interview of the writers at ComicCon saying that Moriarty is DEFINITELY dead. But who knows.

I really hope he is dead, I'm kind of over him. I doubt the explanation of how he faked it could be satisfactory.