Possible scenario, for those interested in such details: in Spain-posthumous daughter of Juan de Asturias lives. In Austria-Emperor Maximilian I has a son with Bianca Maria Sforza, who succeede him as Holy Roman Emperor, meanwhile Charles Habsburg rules in Low Countries, not being King of Spain, he looks for wife closer to home and marries Mary Tudor the Elder. Then on British Isles we have chain of events a bit similar to that from Iberia IOTL: James V of Scotland dies as child, just like all his siblings did IOTL, while Henry VIII has jousting accident and suddenly Charles Habsburg's wife has the best claim to the throne.