It depends what happens in that time. I'm assuming that at some point they're going to resolve *that cliffhanger*. Having said that, the timeline for this series was completely bonkers- nothing at all in February and then TBB and TGG literally right on top of each other. So who knows?
In theory if there's a big time gap I can probably develop Sherlock/John so it's you know, actually Sherlock/John instead of Sherlock just sort of you know, creeping on John...
Who knows? I don't. I go where the producers lead me, no matter how twisty or batshit lol.