Norm Smith medallist Hayes, 34, is retiring at the end of the AFL season and has been mentoring first-year player Dunstan.
Former club champion and 230-game player Nicky Winmar also wore the No.7 for the Saints in the 1980s and 1990s.
Three-time club champion Hayes has played 293 games including 16 in 2014. He has averaged 24.8 possessions and was last month rated by captain Nick Riewoldt as a strong chance to win a fourth best-and-fairest award.
Midfielder Dunstan was recruited from SANFL club Woodville-West Torrens at pick No.18 in the 2013 AFL draft.
The 19-year-old has played 16 games in the No.36 guernsey in his debut season, averaging 18.7 disposals in 16 matches.
"That's something we'll talk about over the next few weeks," Hayes told FoxFooty's On The Couch program on Monday night.
"But he's certainly a guy I've worked really closely with and I love the way he goes about it.
"So I could see him fitting very nicely into it. But yet to make a decision on that."
Triple All-Australian Hayes has been adored by fans across the AFL, not just for his courage but for his side-stepping, which has earnt him the nickname 'the Candy Man'.
The former Sydney schoolboy said his early cross-code experiences helped him develop his evasive skills.
"It's one of those things I guess I picked up playing a lot of touch football and a bit of rugby throughout my school years," he said.
"I was never overly blessed with pace."
Last-placed St Kilda have four games remaining but only one is a home fixture, which makes Sunday's Etihad Stadium clash with the Western Bulldogs a big occasion for the Saints' fans to farewell their former skipper Hayes.
St Kilda's last three games of the season are away to Sydney (SCG), Richmond (MCG) and Adelaide (Adelaide Oval).
