As "Sherlock" fans prepare for the inevitable end of season 3 this weekend, it appears season 4 and 5 are already in the planning stages.

Recently, Steven Moffat confirmed that he is already planning future seasons and episodes of the hit BBC series.

“Rather excitingly, Mark and I, for no particular reason, we just got out of the rain and sat at the top of the ['Sherlock'] production bus… and we just started plotting out what we could do in the future,” said Moffat according to Radio Times. “And we plotted out the whole of series four and five.”

“So we have got plans – but our plans don’t tend to be ‘Let’s blow up the world or cast the most famous person in the world’ they tend to be ‘What exciting twists and turns can we add to this?’ And I think we’ve got some crackers! The ideas we had that day, I thought were the best we’ve ever had.”

Meanwhile, producer Sue Vertue affirms that with Benedict Cumberbatch and Martin Freeman dealing with prolific movie careers, scheduling is already underway to film "Sherlock" season 4, and possibly 5.

"We're working on it—it's dates," said Vertue according to Telegraph.

But what's going to happen if Benedict Cumberbatch is too busy to portray Sherlock Holmes?

Actress Emma Thompson appears to have a solution: Cast a woman.

“I have always been a huge Sherlock Holmes fan,” said Thompson. “I would love to play a character like that, but that’s a problem if you’re a female. I’m always likely to be overlooked for not being male.”

The "Sherlock" season 3 finale will air this Sunday on BBC.