If Przemysł II survives we see a conflict between him (and probably allied with him Władysław the Elbow-high) and Wenceslaus II for Poland. Przemysł controlled Greater Poland (Wielkopolska) and Pomerelia with Gdańsk. At the same time, Wenceslaus controlled Little Poland (Małopolska) and Cracow. Przemysł temporarily gave up those lands, but I think it was only a tactical move. To be honest, I would put my money on Wenceslaus.
A lot depends of the time of Wenceslauses (?). And if Przemysł II lives and remains king of Poland, then Władysław the Elbow-high is only a minor duke, so his son has poor chance of marrying Anna. Przemysł II's son, OTOH...
IIRC Przemysl was murdered in 1296, so a POD might be there. Wenceslaus III was born in 1289, but he had younger brothers (and an older one, who did live long) though they didn't reach adulthood.
Anyway a POD probably should be within this timeframe.
IIRC Przemysl II didn't have a surviving son IOTL. Who would have been the designated heir of Przemyshl, if he had remained without a male heir. Would it have been the husband of his daughter, or (agnatically) the then most senior male member of the house of Piast. Depending on how distant relatives they were, or Papal dispensation, both lines could be married.
Especially in Bohemia, the Holy Roman Emperor and some of Imperial princes with the means to do so (like the Wittelsbach and Habsburgs) will get involved. A powerful Emperor would declare Bohemia a reverted Imperial fief, this is what (Habsburg) king of the Romans Albert of Austria did in 1306. Holy Roman Emperor Henry VII of Luxembourg, also got involved in 1310, but he married his heir to a Premyslid heiress, Elisabeth.
In 1296 the heir of king of the Romans Adolf of Nassau, was married to the elder sister of Anna and Elisabeth, Agnes, but she died the same year.
Not to mention that by this point Adolf of Nassau already was in conflict with the majority of the Prince-Electors and the house of Wettin, due to his attempt to expand his powerbase with Thuringia and , if possible, Meissen too.
Then there also is the situation in Hungary, Charles Robert, wasn't too sure he would succeed. In 1296 there were still Arpads OTL Ladislaus IV and OTLAndrew III. The house of Wittelsbach also had a good claim, like OTL Béla V (Otto).
Involvement of the Empire in disputes in Poland and Hungary seems less likely given the shape of the Empire and the position of the Emperor; by this point it would require a powerful and successful Emperor to reign long enough to be able to use any of the Imperial claims the Empire had towards those two realms (in part due to proximity; in theory it is derived from being The Christian Empire (due to the relation with the Church) etc.), still the status of such claims can be classed as disputed. Bohemia OTOH was a part of the Empire and the Emperor, as liege, was in a better position to get involved.
