I should clarify. The USPS has several policies regarding stamp issues. One of them is that each president has a stamp issued in his honor within one year of death. The most recent was George HW Bush. Living presidents are not allowed the honor. But I'm sure they have plans in the works for Presidents Carter, Clinton, GW Bush, Obama, Trump, and even current President Biden. I specifically asked about Trump because of the widespread love and widespread hate for him.
Edit to the person who asked about Pierce, Ford, and Nixon. Franklin Pierce has been honored twice-once in 1938 and once in 1986. The Richard Nixon stamp was issued in 1995 and the Gerald Ford stamp was issued in 2007. Here's an informative article for those who are interested: https://en.wikipedia.org/wiki/Presidents_of_the_United_States_on_U.S._postage_stamps