POD is simple-Duke of Cracow Leszek Czarny (Leszek the Black) is not impotent and have a son from his marriage with Gryfina of Halych (Bolesław, born in 1270). So with reigning Duke of Cracow leaving adult son (IOTL Leszek died in 1288, but without OTL humiliation and less stress he could live a bit longer) upon his death said son is obvious heir of father. What else changes?
-IOTL throne of Cracow was contested between numerous dukes after childless death of Leszek (Henry the Righteous of Wrocław, Władysław Łokietek, Przemysł II of Greater Poland, Bolesław II of Mazovia and Czech King Wenceslaus II). ITTL succession should be more smooth, although Henry the Righteous is likely to still try his chance.
-Wenceslaus of Bohemia based his claim on will of Gryfina, who was his maternal aunt. That was really weak claim-Gryfina was consort of reigning Duke and lacked any rights to Cracow on her own, but thanks to his military strenght Wenceslaus was able to prevail over his rivals. ITTL Gryfina would certainly not support her Czech nephew against her own son.
-Przemysł II would not have opportunity to take royal insignia from Cracow, thus he would not be crowned. His coronation enraged Brandenburgians and costed him life-Brandenburgians murdered him in Rogoźno just few months later. ITTL Przemysł would not be king, but thanks to this he would at least make less enemies. Henry the Righteous also could avoid death, but it is unclear who poisoned him, if his Silesian cousins were responsible he could still be killed (other theory says, that a man whom Henry send to Rome with money to get Pope's permission for coronation has stolen that money and poisoned Duke to avoid consequences of Henry's wrath).
@krieger
-IOTL throne of Cracow was contested between numerous dukes after childless death of Leszek (Henry the Righteous of Wrocław, Władysław Łokietek, Przemysł II of Greater Poland, Bolesław II of Mazovia and Czech King Wenceslaus II). ITTL succession should be more smooth, although Henry the Righteous is likely to still try his chance.
-Wenceslaus of Bohemia based his claim on will of Gryfina, who was his maternal aunt. That was really weak claim-Gryfina was consort of reigning Duke and lacked any rights to Cracow on her own, but thanks to his military strenght Wenceslaus was able to prevail over his rivals. ITTL Gryfina would certainly not support her Czech nephew against her own son.
-Przemysł II would not have opportunity to take royal insignia from Cracow, thus he would not be crowned. His coronation enraged Brandenburgians and costed him life-Brandenburgians murdered him in Rogoźno just few months later. ITTL Przemysł would not be king, but thanks to this he would at least make less enemies. Henry the Righteous also could avoid death, but it is unclear who poisoned him, if his Silesian cousins were responsible he could still be killed (other theory says, that a man whom Henry send to Rome with money to get Pope's permission for coronation has stolen that money and poisoned Duke to avoid consequences of Henry's wrath).
@krieger