Expert fangirling services since 1986.
No matter what else goes in the character’s lives, the center of the show will always be Sherlock and John and their relationship, however you interpret it, because I firmly believe that is the creators’ commitment (as they’ve stated, repeatedly). Other things can happen, other people can come in and go away, but at the core of it all is these two men, their friendship, their adventures, and their life together - in whatever sense they are together. And that will continue to be the case.
And we can always ship whoever we want. If the last two series’ worth of canon didn’t stop us, then the upcoming series’ canon needn’t stop us, either.
*note: I am planning to write later more extensively about the week’s setlock spoilers and why they have me flailing and squeeing like a crazed fangirl (which I am) but they will be tagged and behind a cut, so no fear.