According to a recent Q&A, the BBC considered pulling the plug on Doctor Who when David Tennant left.
This was rumored at the time, and I always thought it was a silly rumor. But no, it appears that cancelling Doctor Who was in fact discussed in the halls of the BBC. They might have questioned the viability of replacing Tennant, and on top of that replacing RTD. Add those together, and the BBC would essentially find themselves launching a new series if they decided to continue Doctor Who.
Thankfully, saner voices prevailed.
Steven Moffat said:He also disclosed that the BBC had considered pulling the plug on Doctor Who after David Tennant left, fearing that nobody else could fill his shoes.
"David owned that role in a spectacular way, gave it an all-new cheeky sexy performance and became a national treasure. And he didn't do it instantly, he did it over time. So the idea that Doctor Who could go on at all in the absence of David was a huge question," Moffat said.
"I didn't realise how many people thought it wouldn't succeed at all. That was quite terrifying when I found out about it later.
I think there were plans maybe to consider ending it. It was Russell saying, you are not allowed to end it." Source
This was rumored at the time, and I always thought it was a silly rumor. But no, it appears that cancelling Doctor Who was in fact discussed in the halls of the BBC. They might have questioned the viability of replacing Tennant, and on top of that replacing RTD. Add those together, and the BBC would essentially find themselves launching a new series if they decided to continue Doctor Who.
Thankfully, saner voices prevailed.