Taylor, Madonna and Dua all could do it, all worthy of doing it and will be in their touring lifecycles to do it. Also creates a rare op to have three female headliners if a statement wants to be made (without it feeling like its been done to make a statement).
Whether that's all too "poppy" for Glasto that's another thing, but if you combine it with a more traditional Other lineup they may just about get away with it.
(Riri will have a 10 month year old by that point, highly likely she ain't be doing it....pencil her in for 2025 though).