The Grand Moffat has spoken, according to this article, even though the fans of both shows have been asking for it, there will be no crossover between the two very popular shows, Doctor Who and Sherlock.
The Reason? Well see, this is where I think Mr. Moffat’s logic starts to fall apart. It is not because the two main characters are so similar that you would have a hard time finding a problem one could not solve on his own, no it is because if Sherlock lived in the same Universe as The Doctor, you would have to admit that time travel is possible and the Daleks have invaded the Earth. Apparently Moffat believes a Sherlock story cannot exist in a world where Time Travel is possible. Guess the Whoniverse is just too timey-Wimey for Sherlock.
A good crossover story would be extremely hard to write, especially if the sci-fi elements were kept at a minimum. But I believe it could be done. Maybe that is what Moffat is really saying, at least modernly, a typical Doctor Who story is anything but subtle. Do you agree?