Keary played 24 matches for Souths last season, scoring four tries.
He is off contract at the end of the season and has reportedly attracted interest from other clubs.
The Ipswich-born upcomer signed with the South Sydney Rabbitohs in 2012 but has always had ambitions to play with the Brisbane Broncos, the side he followed as a child.
Keary made his debut in round 12 of the 2013 season and scored the first two tries of his professional NRL career in round 20 that year.
The next year, 2014, Keary played 12 matches. He was five-eighth during the Grand Final when the Rabbitohs won the premiership - breaking their 43 year drought.