John Sigismund would naturally keep his rights on Transylvania only and would be heir of Ferdinand in Poland only if he had no half-brother... Ferdinand jr not Isabella would be King of Poland in this scenario... Still Isabella would secure at least TransyIvania for her eldest son and the crown of Poland for her descendants... not the best deal but not a bad one... plus nobody can say what would happen in the election after Ferdinand’s death...
If John Sigismund still died without heirs then Transylvania would go back to the King of Hungary...At that point, there is no union of Lublin, so even if no one can say what would happen during an election in Poland after Ferdinand's death, one could easily predict what would happen in Lithuania after Ferdinand's death. And what if John Sigismund had died like IOTL and had half-brother? To whom would Transylvania go - to his Habsburg half-brother? And main line of Habsburgs would happily ignore their cousin becoming a new prince of land which they claimed for themselves?
If John Sigismund still died without heirs then Transylvania would go back to the King of Hungary...
unless relations between Austrian and Polish branches were really bad, as in that case is likely Ferdinand and Isabella‘s son will at least try to claim Transylvania...
Well we would see how things would go there... Turks are another factor (and involved only about Hungary, were they were the enemies of the Habsburgs). Transylvanians also can decide of their own to find another ruler if they do not want the Habsburg (but that is secondary and not relevant about Poland). I am not expert at all about Lithuania so I have no idea of what will happen there at Ferdinand’s deathAnd Turks would totally allow that, and everyone would be ignorant of what it means. The idea of Ferdinand jr. - Isabella marriage is very flimsy at best. And who said that Transylvanians themselves wouldn't have a say in who would govern them?
Well we would see how things would go there... Turks are another factor (and involved only about Hungary, were they were the enemies of the Habsburgs). Transylvanians also can decide of their own to find another ruler if they do not want the Habsburg (but that is secondary and not relevant about Poland). I am not expert at all about Lithuania so I have no idea of what will happen there at Ferdinand’s death
Sigismund the Old, who is already dying, would do nothing indeed, but Bona would remain active. Considering the fact, that she tried to marry widowed Isabella to Ferdinand Jr. and even to widowed HRE Charles V she'd has nothing against Habsburg archduke (IOTL there were Habsburgs who refused her, now situation is different). Also, Isabella, who acted as regent for her son, tried to exchange it for Duchy of Opole with Ferdinand I and left unstable Hungary with her son, unfortunately Opole was ruined after being badly managed by Georg Hohenzollern and Isabella had to return to Transylvania. ITTL she'd take John Sigismund to Poland if she's queen, meanwhile nobles of Transylvania are likely to rebel, as they did several times before, and replace John Sigismund with other ruler with Sultan's blessing.
Did they depose Stephen Bathori once he became king of Poland? No, they didn't. They likewise won't depose John, even if he succeeded his grandfather immediately (which is more likely not to happen).
Isabella left Transylvania voluntary in 1557 with intention to never return, as she could not whitstand pressure of being regent in such unstable country-Ferdinand proposed her Duchy of Opole, which was previously in hands of Georg Hohenzollern (who complety ruined it-so Isabella lacked even proper residence and thus was forced to return to Transylvania).
Bathory was adult man who had good relations with Sultan, John Zapolya would be kid with Habsburg stepfather.
But Ferdinand sr had already won in Hungary, at least respect Isabella and her son, or he will won together with the wedding of Isabella and Ferdinand jr. John Sigismund, if he survived and Isabella had at least a surviving son by Ferdinand jr, will likely marry one of the younger daughters or granddaughters* of Emperor AND receive some good lands. If Isabella and Ferdinand had no surviving son then a surviving John will be likely the heir of his stepfather in Poland and Lithuania (and again married to an Austrian girl)But you cannot project Isabella-Ferdinand jr. marriage while simultaneously ignoring Hungary, which is first priority for Ferdinand Sr. who is the one deciding about Ferdinand Jr.'s marriage. I cannot fault you for not being expert, but we should at least look at Lithuania, which would be very divided internally. The biggest magnate family of Lithuania, Radziwiłłs were both protestant and with family ties to Hohenzollerns, so I'd expect them to support Joachim over Ferdinand.
But Ferdinand sr had already won in Hungary, at least respect Isabella and her son, or he will won together with the wedding of Isabella and Ferdinand jr. John Sigismund, if he survived and Isabella had at least a surviving son by Ferdinand jr, will likely marry one of the younger daughters or granddaughters* of Emperor AND receive some good lands. If Isabella and Ferdinand had no surviving son then a surviving John will be likely the heir of his stepfather in Poland and Lithuania (and again married to an Austrian girl)
Because things do not always follow plans? And the real problem there were the Ottomans, not Isabella and John Sigismund.... But with a common interest in securing Poland and a wedding between Isabella and Ferdinand jr is likely who things in Hungary will go much smoother than OTL, at least about John Sigismund and TransylvaniaHad he? So why Habsburgs had to wait until 1687 for total reunification of Hungary under their sceptre?
Because things do not always follow plans? And the real problem there were the Ottomans, not Isabella and John Sigismund.... B
Well in OTL Ferdinand I archived something big, at least temporarily, around this timeframe regarding Isabella and Johh Sigismund. Having that deal a little earlier and made permanent with the wedding of Isabella and Ferdinand Jr once the Polish crown enter in play is not unlikely at all as that wedding is the best way for getting Polish crown for both spouses over the competition of her half-sister and Hohenzollern husband...Winning implies that you achieved something in real life, not only in plans, so it doesn't match Ferdinand's experience in Hungary.
Well in OTL Ferdinand I archived something big, at least temporarily, around this timeframe regarding Isabella and Johh Sigismund. Having that deal a little earlier and made permanent with the wedding of Isabella and Ferdinand Jr once the Polish crown enter in play is not unlikely at all as that wedding is the best way for getting Polish crown for both spouses over the competition of her half-sister and Hohenzollern husband...
Well is not like they had chances to get that crown before Sigismund Augustus death or who they had seen the path for the Polish crown free after that, not with both the over ambitious Bona and Ferdinand I (husband to Hedwig’s cousin) around... If Poland and Lithuania had a male preference kind of succession then they would have reason to be angered, but as we are talking about a different system of succession I think pretty unlikely they would be surprised by the alliance between their rivals... and Ferdinand jr, without big hereditary lands of his own, son of a Jagiellon princess and husband of another is surely a more attractive candidate for Poland than the elector of Brandenburg... Pretty likely who the elector of Brandenburg, who was an ally of Charles and Ferdinand, will never make serious plans over PolandI imagine the Hohenzollerns will be more than a bit miffed at the Habsburgs for that, then?
Well in OTL Ferdinand I archived something big, at least temporarily, around this timeframe regarding Isabella and Johh Sigismund. Having that deal a little earlier and made permanent with the wedding of Isabella and Ferdinand Jr once the Polish crown enter in play is not unlikely at all as that wedding is the best way for getting Polish crown for both spouses over the competition of her half-sister and Hohenzollern husband...
Well, you are wrong here or are mistaking Hohenzollern branches, as the elector Joachim II Hector was an ally of Charles and Ferdinand (including in Hungary) and NOT yet fully protestant at the death of his father-in-law (he would become openly protestant ONLY in 1555 so 7 years after Sigismund I’s OTL death and started to get oriented towards it only after his own father‘s death in 1535 (and better from 1539). Here we are not talking about Oppeln, who can be repaired with time and becoming a fit land for John Sigismund, but about a wedding (who will put forever Isabella in the Austrian‘s sphere) and the crown of PolandHe achieved this purely on paper, Oppeln was too destroyed for Isabella to give up Transylvania. Hohenzollerns won't abandon hopes for Polish crown and protestants and most of nobles of northern Poland would support Hohenzollern and his candidature over Ferdinand jr, because it's in their interest. Joachim wasn't ally of Charles and with certainty, he wasn't ally of Ferdinand, who hated Hohenzollerns as a whole.
Well is not like they had chances to get that crown before Sigismund Augustus death or who they had seen the path for the Polish crown free after that, not with both the over ambitious Bona and Ferdinand I (husband to Hedwig’s cousin) around... If Poland and Lithuania had a male preference kind of succession then they would have reason to be angered, but as we are talking about a different system of succession I think pretty unlikely they would be surprised by the alliance between their rivals... and Ferdinand jr, without big hereditary lands of his own, son of a Jagiellon princess and husband of another is surely a more attractive candidate for Poland than the elector of Brandenburg... Pretty likely who the elector of Brandenburg, who was an ally of Charles and Ferdinand, will never make serious plans over Poland
If Isabella marry Ferdinand jr you can be sure who, whatever happen in Poland, the weddings of her younger sisters will be arranged by either Bona or Ferdinand and yes would be very different from anything arranged by Joachim Hector. Here the girls will marry Habsburg relatives/allies (not Archduke Charles as he is way too young)That makes sense to me.
I imagine that if Isabella marries Ferdinand Jr and becomes queen of Poland, the marriages for Anna, Zofia and Katarzyna arranged by the Habsburgs will differ from matches arranged for those same three ladies arranged by the elector of Brandenburg, no?