Doctor Who: Series 13 Trailer Breakdown - 20 Things You Must See
2. The Timeless Child's Portal
Some people hope that Chibnall retcons the Timeless Child twist in Series 13. Some hope that he ignores it. Some want him to explore it further. And countless others are probably sick of talking about it at this point. Raises hand.
Regardless of which camp you're in, you can't deny that the portal we see in the above shot looks very similar to the portal through which the Timeless Child originally fell.
If the Doctor is feeling a little burned by the whole Timeless Child thing, it only makes sense that she'd seek out some answers for herself - and her best shot at finding those answers would be to head through that original portal.
If this isn't the Timeless Child's portal, then it could be the Gallifreyan boundary seen in the Series 12 finale. Maybe Series 13 will take us back to the Time Lords' ravaged planet - which, again, would make sense if the Doctor is desperate for answers.