Sorbs are not Poles or Czechs, although they're close to them genetically.
Genetically and linguistically. Upper Sorbian is closer to Czech, Lower Sorbian is closer to Polish.
If Poland had succeeded in keeping control of Lusatia for a longer time, probably the Sorbs would have been integrated into the Poles
That's a typical "what would happen if ..." question. Maybe yes or maybe not. Just think of the Pomeranians (Kaszubi) who had long resisted the attempts by the rulers of Poland in the Middle Ages to include them into the Piast monarchy. Pomeranians of the East who eventually found themselves within Poland and continued there until 1772 have managed to ratain their Slavic dialect now officially recognized as the Kashubian language.
Parts of Upper Lusatia (known as "Milsko" in the Middle Ages ) and parts of Lower Lusatia were incorporated into Poland as a result of the treaty of Budyšin of 1018 between Bolesław Chrobry and Henry II and remained Polish until 1031. The first Sorbian anthem Hišće Serbstwo njezhubjene
by Handrij Zejler was inspired by the Polish national anthem: Jeszcze Polska nie zginęła
. Polish historian Wilhelm Bogusławski wrote the first book on the history of Sorbs which was published in Sankt Petersburg (Russia) in 1864 and later in 1884 re-published in the revised version in Budyšin as Historije serbskeho naroda
In the course of history Lusatia also formed part of the Kingdom of Bohemia and at one time parts of it belonged to a Silesian duke of the Piast dynasty (which one I have forgotten - there were so many of them!)
Help! I'm sorbish and live in Budyšin in Lusatia
Do you speak Sorbian? Have you learned Sorbian at school? Have you heard of Domowina?