For those who have “strong faith and a firm mind in every form of godliness,” miracles still happen, and angels still minister to them. See commentary at Moroni 7:22–23 and 7:26–28.
“Neither Have Angels Ceased to Minister Unto the Children of Men”
The role of angels is to call men to repentance, to help fulfill the covenants of the Father, and to prepare the way for the Savior by declaring his words to the chosen vessels of the Lord so they can bear sure testimony of him. See “Angels Are Coming to Visit the Earth” in commentary at 1 Nephi 3:29–30.