Warning! The following contains spoilers for the Doctor Who Season 11 premiere "The Woman Who Fell To Earth." Read at your own risk!
The first episode of Doctor Who Season 11 is in the books, and the world finally got a chance to witness the Doctor's first television adventure as a woman. We make that whole "first television adventure" distinction because Jodie Whittaker's Doctor said onething very peculiar while getting her new wardrobe in order, and it has us quite shook. The Doctor said it's "been a long time" since she's bought women's clothes, but what was she referring to, and what does that mean, if anything, for the franchise going forward?
True, there are lots of reasons why the Doctor could have purchased women's clothes in the past, but the most interesting and arguably shocking reason would be that the Doctor has been a woman before. That's right, new showrunner Chris Chibnall may not have only revealed the first on-screen female Doctor, he might've also revealed that Jodie Whittaker's Time Lord isn't technically the only time femininity has been guiding things. If true, that's a huge revelation that rocks the Doctor Who lore, and would naturally explain why it has been a "long time" since the Doctor has purchased women's clothes.
Provided the statement is true, this opens up the possibility for Doctor Who to introduce one or more female Doctors who possibly came before William Hartnell's run, which would also assume true theories about the Doctor having previously found ways around the twelve-regeneration rule. Or, alternately, that there was a point during one of the previous eleven Time Lords' cycles that some form of sci-fi magic temporarily changed a Doctor's gender. There are probably other ways to introduce the concept, too.
For the show, it sounds like a perfect way to bring in a high-profile female actress to play a former female Doctor for a one-off episode down the road, similar to what John Hurt's Doctor did. One thing that doesn't seem possible at the moment is for any female Doctors to have had any full cycles occurring between any of the presently known reincarnations of the Doctor. Especially given Whittaker's estimation of it being a "long time" between such clothing purchases.
Unfortunately, Jodie Whittaker didn't follow up that line with a wink to the camera and a promise we'd understand later on in Doctor Who Season 11. This may be one of those statements that gets debated and theorized upon by fans for years until the Doctor Who team finally decides to stop torturing everyone by explaining it during a later season. Until a genuine reason arrives, though, we can't really get too invested, as not to form theories that are potentially far more exciting or game-changing than anything we'll ever see on the show.
After all, the Doctor only stated that it's been a long time since she's bought women's clothes, not that she'd ever worn them. The Doctor has provided outfits for female companions in the past, so it's not crazy to think she's referring to clothes bought for any one of them.
At the same time, if a female Doctor existed long before that stretch of male Doctors, wouldn't it make sense for the TARDIS to have a healthy wardrobe of women's clothes around there somewhere? Let's also remember the Doctor is a an alien seemingly unbothered by traditional gender norms, so wearing women's clothes despite physically looking like a man wouldn't be a strange thing to happen. Ah, the joy of Doctor Who theories, how we've missed you!