William the Rich was duke of Julich, Cleves and Berg from 1539 until his death, but he also controlled the Duchy of Guelders for five years (1538-43) before being forced to yield it to Charles V in the Treaty of Venlo. What if he managed to hold on to Guelders for whatever reason? Say the French gain the upper hand in the Italian Wars and come to his aid or something.

What would this hypothetical duchy of Guelders-Julich-Cleves-Berg look like? Could it affect the Protestant Reformation somehow?