What about a one-off ep of Sherlock before s4? Martin spilled this possibility on Chatty Man last week; see HuffPo for the scoop!
Or, to be honest, anywhere, since they all say the same thing. It's probably what Martin said on the 25-April-2014 episode of Chatty Man.
=grin= The tease.
SPOILERS FOR S3: In case that wasn't enough, Cultbox has begun collecting their ‘Sherlock’ Series 4 news summary, as of 18-April-2014. These are Things Team Sherlock -- cast and creators -- have said. If you haven't seen the s3 finale, don't read that link!
Here's my second try at providing Benedict and huskies, aka Snowbatch. He was in British Airlines' High Life Magazine. It's a lovely article.
Their picture gallery is here.
If you didn't see The 10 stages of a #Cumberbatch Twitter storm, it also has Ben-in-Finland pictures. 8)
Benedict Cumberbatch: my London also via High Life.