Johnson, 18, disappeared for more than 48 hours in mid-November, sparking a search by the Texas A&M University Police Department before he was found in his hometown of Dallas.
The Dallas Skyline High School product has returned home to his family, and Sumlin said Johnson is trying to sort out his future options.
"That's an ongoing process right now," Sumlin said Wednesday. "I think he's trying to decide where he is, if he's coming back, if he comes back next semester, if he's going to take the year off or if he's going to transfer. In my conversations with him that's where he is. He's just trying to figure out what his next step is going to be."
Sumlin said Texas A&M's coaches and players will be behind Johnson in whatever he decides.
"We're going to support him in any of those three [options]," Sumlin said. "That's his decision and he's with his family and is trying to figure it out."
Johnson appeared in 10 games this past season, making 30 catches for 339 yards and a touchdown. He was an Under Armour All-American coming out of high school and was ranked as the No. 33 player in the ESPN 150 and as the nation's No. 3 receiver when he signed with Texas A&M. He originally gave his verbal commitment to Texas but decommitted and later committed to the Aggies.