With the impending departures of Peter Capaldi and Steven Moffat from Doctor Who change is certainly in the air. We already know that the incoming showrunner will be looking for a new lead actor but what other elements in the show could be up for a redesign?
Every era of Doctor Who can be identified as a reflection of those in charge. During the classic series, it was often a combination of the Producer and Script Editor. For example, Barry Letts and Terrance Dicks, Philip Hinchcliffe and Robert Holmes, Graham Williams and Douglas Adams were combinations responsible for approaching Doctor Who in a particular manner. In the modern era these two roles have merged somewhat. Although the role of Script Editor still exists, the head writer has also become an Executive Producer and is ultimately responsible for the creative direction of the series as a whole. However one notable Producer of the classic series also took these decisions and made his mark on the show.
John Nathan-Turner (from ‘The Leisure Hive’ 1980)

When JNT took on the role of Producer he began by making changes. Tasked with taking the programme into the 1980’s the revamp of the show’s presentation was radical. There was a new title sequence with a redesigned logo. The theme tune arrangement received an update. A new TARDIS exterior prop was also commissioned. Although small changes, these were to key and recognisable elements of the show. The visual shift between ‘The Leisure Hive’ and ‘The Horns of Nimon’ which preceded it, is therefore stark to say the least. Tom Baker’s costume was also not immune from reinvention. Although the iconic scarf was retained the whole ensemble was improved. The ‘undergraduate’ scruffiness was dispensed with in favour of a more mature appearance which fitted the now older Doctor.
The following season JNT was able to cast his own vision of the Doctor in the form of Peter Davison. The TARDIS console too would receive a revamp for Davison’s debut season before being completely replaced in 1983. Over the course of his record tenure, Nathan-Turner would’ve deliver frequent changes but usually in the form of casting. However, when initially bestowed with creative control JNT set the blueprint for which elements of the show would receive updating to signify the change at the helm behind the camera.
Philip Segal (‘TV Movie’ 1996)

Executive Producer Philip Segal was the driving force behind the TV Movie. With input from the BBC’s Jo Wright, Segal was able to convey a vision for Doctor Who that would be produced in Vancouver which required constructing Doctor Who from scratch. Inspired by that which had gone before new designs of the TARDIS interior and exteriors were delivered. A new title sequence and theme was also required. Even a returning Seventh Doctor received an updated costume. His successor, played by Paul McGann, also provided a new interpretation on the lead role. Curiously the only element not to receive a nineties update was the logo. Instead of something new the Doctor Who logo from 1970-1973’s Jon Pertwee era was tweaked and reused.
Russell T Davies (from ‘Rose’ 2005)

Like Segal, Russell T Davies also had the task of rebuilding Doctor Who from scratch. All the elements had to be reimagined. So, once again, the TARDIS interior and exterior, title sequence and theme tune were all new variations inspired by those seen before. The Doctor (Christopher Eccleston) too was reimagined with a character and a costume that hadn’t been seen before. Unlike the TV Movie, RTD also elected for a completely new logo which provided a clear label for his particular era of the show. It would also become an era highlighted by the modernisation of established elements such as the Daleks, Cybermen and Sontarans. Having triumphantly brought the show back whoever followed RTD had a tough task and would need to define their own era.
Steven Moffat (from ‘The Eleventh Hour’ 2010)

A strategy of widespread stylistic changes was employed by Steven Moffat when he took over from Russell T Davies. Just as John Nathan-Turner had done, Moffat approached the same features looking to update them. In addition to casting a new Doctor, all the traditional elements were afforded a revamp to distance his new version of the show from what had gone before. The TARDIS exterior was given a fresh paint job and an appearance closer to the Peter Cushing movies of the Sixties, complete with St John’s Ambulance badge. The inside of the TARDIS was also completely redesigned for Matt Smith’s debut series. Following tradition a new title sequence, logo and theme arrangement were all created that firmly stamped the imprint of the Moffat era on the show. The decision was also made to update the Daleks but the least said about that the better.