https://profootballtalk.nbcsports.com/2018/12/31/are-steelers-moving-toward-a-divorce-from-antonio-brown/
Based on his contract, not much — without taking a massive cap hit. Thanks to a $19 million signing bonus paid in 2017 and a $12.96 million restructure bonus paid in 2018, the Steelers would carry $21.12 million in dead money if they cut or trade Brown. (They could release him in March with a post-June 1 designation, resulting in $7.04 million counting against 2019 and $14.08 million counting against 2020.)
Whenever a decision is made, something needs to happen by the fifth day of the league year, which begins in March. That’s when Brown earns another $2.5 million roster bonus. Presumably, the Steelers would want to cut or trade him before then.