Yep, I’ve many actually. Well, Johnlock isn’t a headcanon anymore since I watched the pilot. I’ve a feeling that Janine is Moriarty’s sister…what do you think? Moriarty’s has a brother according our Sir Arthur and, may be, Mark and Steven put Janine as his sister now.
Also, I guess Irene might appear sometime…and there’s Mary. Misterious magnificant Mary. Well, this is all theories I made. If I start to talk about my ships, I’ll never end this answer.
Don’t you think is very weird that Molly doesn’t get fired for faking Sherlock’s death register? I know she helped him (I kinda ship Sherlolly too), but the hospital wouldn’t let this pass unnoticed. But our lovely writers will say it all, I hope so. We just have to wait til 2016.

Thanks Gatiss and Moffat