It is possible for Wenceslaus' descendants to unite whole Masovia. However, if the Hussites are not butterflied away, I doubt they would have offered the throne to a Masovian duke; they offered it to king Władysław II and duke Vytautas the Great of Lithuania to gain a powerful ally. Even united Masovia would be a little too weak, IMO. But, theoretically, it is possible. Eventually hussites desperately needed a king, they even considered Sigismund Korybut.
A marriage between a Masovian duke and a Luxembourg princess is even less likely, since it had been Luxembourgs who temporarily had lost the Bohemian crown to the Hussites. Such a marriage would have been an act of acceptance of the Hussite uprising. Although... Had Sigismund of Luxembourg died in right moment, theoretically it might have been possible to arrange such marriage as a compromise - Luxembourgs, in a way, would have kept Bohemia (at least partially) and the Hussites would have been spared a longer war - Bohemia alone was not able to keep fighting forever. Personally, however, I consider it very unlikely.