Say Joachim II, Elector od Brandenburg (1505-1571) happened to be staunch Catholic like his father-in-law, George the Bearded of Saxony. Considering the fact, that both his wives were also daughters od devout Catholic monarchs, Joachim's Catholicism is likely to pass to next generation of Hohenzollerns. Also, Catholic Joachim is likely to more actively support Charles V in Schmalkaldic Wars, not even mentioning the fact, that his two wives were of Jagiellonian descend (Magdalene was granddaughter of Casimir IV, Hedwig was daughter of Sigismund I), so beside skewing religious landscape of Germany in favour of Catholics (now Catholics have 5 electorates, Protestants just 2) Joachim's Catholicism makes dynastic or personal union between Brandenburg and Poland-Lithuania very likely, how would situation in the region develop in such case? Brandenburg as northern Austria's analogue attached to bigger realm outside HRE?