The BBC’s open tender scheme is not new, it’s just new to Doctor Who. IP remains with the BBC on all tendered contracts. Besides, they’re not letting one of their biggest properties get out of their total control. The only time they ceded IP rights to an external producer was for the movie, and what a headache that was.

But if you really need reassurance, this from the BBC Commissioning site:

The BBC retains all IP in Doctor Who. BBC Studios will continue to lead the global distribution of Doctor Who as well as licensing, consumer products, digital and immersive experiences on behalf of the BBC.