Richardson tweeted Jan. 21 that he was reopening his "recruiting process to explore my options to better my future academically and athletically." He committed to Maryland on Tuesday.
Weaver decommitted Monday after being told by Michigan coach Jim Harbaugh that there was a 50-50 chance the Wolverines wouldn't have room for him in the 2016 class.
Elliott, who played at Westside High School in Houston, received a Texas-shaped birthday cake from Harbaugh and then-defensive coordinator DJ Durkin in November.
Rumors of a change in heart for Elliott have been swirling for weeks, but he had gone out of his way to dispute the chatter, saying he was 100 percent committed to the Wolverines.
In early January, Elliott said he was communicating with Michigan coaches only. But a few weeks later, he posted a picture of himself with a few Texas coaches during an in-home visit. On Saturday, Elliott tweeted a picture taken during his official visit to the Longhorns.
The Michigan staff seemed prepared for this departure; the coaches flipped former Penn State defensive tackle commit Michael Dwumfour on Monday. Michigan still has No. 1-ranked defensive lineman Rashan Gary on its board too.
Elliott plans to announce his decision Wednesday, and all signs point to Texas as his final landing spot.