Wade has spent nearly 14 of his 15 NBA seasons with the Heat, while Haslem has played his entire 15-year NBA career in Miami.
Last month, Riley made it clear that he wanted to bring Wade back as a player in 2018-19 despite his production drop-off in recent years.
The Heat have some competition for D-Wade's services, though, as the Zhejiang Golden Bulls in China reportedly offered him a three-year, $25 million contract, per Sportando.
After playing 13 seasons for the Heat, during which he was a 12-time All-Star, one-time NBA Finals MVP and three-time NBA champion, Wade signed with his hometown Chicago Bulls in 2017.
Wade received a buyout after just one season and reunited with LeBron James as a member of the Cleveland Cavaliers.
The 36-year-old veteran appeared in just 46 games with the Cavs last season before he was traded back to the Heat.
In 67 contests split between the Cavaliers and Heat last season, Wade averaged a career-low 11.4 points to go along with 3.8 rebounds and 3.4 assists.
The 38-year-old Haslem has played sparingly over the past three seasons, appearing in a total of 67 games during that time.
Last season, Haslem averaged a career-low 0.6 points and 0.7 rebounds in 5.1 minutes per contest.
He hasn't started more than 25 games in a single season since 2012-13, and he is far removed from a four-year stretch from 2006-07 through 2009-10 that saw him average at least 9.9 points and 8.0 rebounds per game in each campaign.
Haslem's 844 games played are second in team history behind Wade's 876, though, and he is a respected leader with three NBA titles to his credit.
With 13 players under contract, the Heat have left themselves room to sign both Wade and Haslem.
If they do return to Miami for the 2018-19 season, Wade will be part of a deep backcourt that includes Goran Dragic, Wayne Ellington, Dion Waiters, Josh Richardson and Tyler Johnson, while Haslem will likely act as the equivalent to a player-coach.