I've read that Anne Boleyn had a defect that prevented her from successfully giving birth to more than one child, so what if instead of giving birth to Elizabeth she gave birth to Edward VI? Does Henry VIII try to get rid of her when she can't give him any more children, or does giving him an heir mean she keeps her head? What type of King would this Edward VI grow up to be depending on how his father treats his mother?
The other big question I have for this scenario is what happens to Mary, Queen of Scots? Let's say she is born and her father dies as per the OTL, is there any way for the English to keep the Treaty of Greenwich in effect and have her raised in England from age 10 until she is married to Edward? How does this affect her views on the reformation as well as the views of the Scottish people toward it, and is it possible for the Acts of Union between England and Scotland to happen earlier with a successful marriage and male heir between Mary and Edward?