Walker, who is contracted until 2021, has been a shell of his best over the last few seasons, having booted 10 goals from eight games in 2020.
And Brereton believes the ability for Walker to continuing on next year might be a “bridge too far”.
“He (Walker) has always been regarded as a better footballer than what perhaps his physical prowess has allowed him to be,” Brereton told SEN’s Bob and Andy.
“He is one of the most gifted kicks of the footy that we’ve seen. He could be the best field kick of any key position forward that we’ve seen for 20 years.
“He’s lost that tiny little spark of the short hard lead-up. Let’s call it an hour for each game for pure game time, I think Taylor Walker’s body is going to be counted in hours for how much longer it can go ahead.
“It’s sad because he’s been very good for Adelaide, he’s been fantastic for them as a player, he’s had his hiccups along the way at certain times, I’ve been critical of him too at times when he hasn’t put his nose over it, but he’s been very good for that team.
“There’s no possible way you could contemplate 2021 with him, I think that’s a bridge too far. He deserves to go out on his terms with this team this season.”
Walker needs to play in three more matches to reach the 200 game mark for his career.