John directs his promise of baptism by the Holy Spirit and by fire to the people as a whole, not the religious leaders, since John speaks of their being baptized, which the Jewish leaders had rejected.
In Matthew 3:11 John is not addressing the Pharisees and Sadducees as he did in the preceding four verses (Matthew 3:7–10), but rather the crowd as a whole. After all, the pronoun you
in this passage needs to be understood as in the first place referring to all those who have been baptized. The Pharisees and Sadducees themselves had not been baptized, however, and it is noteworthy that John here does not speak about judgment as he had in the previous verses but rather of the nature of baptism itself, albeit in very general terms. After having condemned, John the Baptist now also encourages.1
11 “I baptize you with water for repentance, but he who is coming after me is mightier than I, whose sandals I am not worthy to carry. He will baptize you with the Holy Spirit and fire.