This could only happen in a situation in which Henry is trying to get his daughter entirely removed from the political scene, since getting married off to a Polish Prince would be the medieval equivalent of getting relocated to Nome, Alaska.
Perhaps if Matilda did something to displease her father, such as refuse to wed Geoffrey of Anjou, and Henry decided that one of his nephews, or bastards would be better suited to rule than his daughter and grandson. Only in that situation would a Western European monarch consider marrying his eldest daughter even a king of such a peripheral country.
But in terms of plausibility, I think that it would be more likely for Mathilda to end up married to a Kommenid prince than to a Piast. As a member of the Polish court, Mathilida, would be a very marginal figure, since she would have extremely limited influence in only one court that the Polish King actually cared about (the HRE). She would bear a few children, who might grow up speaking French in addition to Polish. Chances are she would favor one of her sons to succeed to the throne, but I doubt Boleslaw would be any more likely to heed his queen in the matter, and would probably divide his kingdom between his legitimate issue.