Here is something that I have seen on a lot of Doctor Who websites and it is quite interesting but makes a lot of sense. Steven Moffat was asked which show he would give up doing first Doctor Who or Sherlock and the answer was one I guessed he would make and that would be Doctor Who and here is Steven Moffat's explanation.
“Eventually, I’ll stop doing Doctor Who because it stops me doing anything else, but Sherlock doesn’t swamp my schedule. I could imagine we’ll come back and do Sherlock fairly often for many years, rather than very often for a few years."Steven Moffat is currently working on Series 8 of Doctor Who the first series of the Peter Capaldi era and with Mark Gatiss is working on the 4th series of Sherlock.
Source: Peter Capaldi News