MICHAEL Hurley's decision to sign with Essendon until the end of 2022 will have no impact on the futures of St Kilda veterans Sean Dempster and Sam Fisher, Saints coach Alan Richardson says.

However, the Saints might have a plan b, with Richardson flagging the possibility of acquiring another backman in the trade period.

Fisher, 34, and Dempster, 32, come out of contract at the end of the season, but Richardson said Hurley's choice did not affect how the Saints will deal with their experienced defensive duo.

"Not really, no. (Jake) Carlisle will play a really significant role for us down back. We think we've got a fair bit in terms of depth. (Hugh) Goddard will be up and running again by the time the season starts," Richardson said at Moorabbin on Friday.

"We've got a couple of young defenders on our list that are certainly going to get opportunities.

"It may be that we look to bring another defender in."

Goddard is recovering from a ruptured Achilles tendon in his left foot.

Richardson, who was an assistant coach at the Bombers when Hurley was drafted, expected the key position player to remain at Essendon.

"It's probably the right thing to do. That group's been through a lot," Richardson said.

"For 'Hurls' to stay with his mates and try to get the footy club back on track makes a fair bit of sense to me. He's that sort of person.

"I always thought that would probably be the way that ended up, so (the re-signing) didn't surprise me at all."

Fisher has not yet been ruled out for St Kilda's final match of the season, against the Brisbane Lions next Sunday at Etihad Stadium, after he hurt his hamstring against the Sydney Swans last Saturday night.

It was the third time he had suffered that injury this season.

He has been limited to 11 matches, and hasn't notched more than 18 in a year since 2011.

"It was not a severe hamstring. It was a bit of a hamstring. There is a chance that he'll play (versus the Lions)," Richardson said.

"There's a fair chance (people will) read into that being his last game. That's not necessarily the case.

"It may be at the end of the year that with someone like 'Fish' that's at his age, that's had a bit of recent injury history, we sit down and talk about what next year looks like, but we'll have to wait and see."