Just some silly questions:
How would the portuguese and the castillian react to ships crossing by their waters with riches? (Notice we are talking of two of the most important naval powers of the early XVI century)
Do you really believe who discovers America is the essential question? ("Oh! What a pity they discovered America, we have better location to explore and take it, we have a bigger navy, they are heretics, but... they arrived first!").
Why would the Habsburg become lutheran? Lutheranism spread among imperial noblemen as a form of rebellion against the Emperor! Having access to more riches the Hanseatic towns would look to differenciate more with the Emperor and if he converted to lutheranism they would go for catholicism!