I could see Aegon "winning" and finishing the series alive and on the IT. Maybe it's not the most likely scenario but it's one to consider.
I see 3 heads of the dragon and I see 3 central conflicts in the book. Jon will have his battle to defeat the night. Danny will have her battle to end slavery and remake Slavers' Bay. Aegon will have his battle for the Iron Throne.
If we see TWOW as setting up the final confrontations, then the book could end by setting up: Jon v The Others, Danny v Volantis, Aegon v Euron*.
TWOW, then would just need to eliminate the other lines or merge them into those 3 battles. This also handles the timeline issue for Danny getting back to Westeros in time for the book to end by ADOS. If Aegon's success makes Danny feel the need to conquer Westeros is less, she can focus on her issues with slavery and go about not being such a tedious read.
*we joke that Aegon and Euron were kind of late editions to the books to be such central characters. it'd be fitting for them to fight each other. Even more fitting because they'd be late-adds fighting for the original throne, and the originals are fighting for "thrones" added later in the book.