Nothing done to succession, at all. It goes sons-daughters-brothers-sisters, so she could only have become Queen if Henry VIII had had no legitimate children. And that's unlikely, since as head of the Church he decides who's legitimate and who isn't...A younger sister of Henry VIII, who died in childhood. WI: She had lived. Possible marriages and what would this have done to the succession?
A more interesting POD is if Henry's older brother Arthur survives long enough to become king.
That would mean Henry is not married to Catherine and chooses different bride. Hmmmm. even that can be interesting, not considering children they will have, no need for marriage annulment and so on.
What makes this truly interesting is that Henry was being groomed to enter the Church, possibly eventually becoming the Archbishop of Canterbury.