But while the Scottish-born forward's contract is due to expire at the end of June, Cummings stressed his immediate intention was to celebrate the Mariners' first title since 2013.
Mariners operate on one of the A-League's smallest budgets and Montgomery acknowledged that Cummings was unlikely to be the only departure.
"We're a selling club, the club needs to sell players to survive," he said.
The possible departures include Montgomery, who has seen his stock rise after overcoming significant financial limitations to end the Mariners' trophy drought.
"The world's his oyster," Cummings said of Montgomery, who took over at the Mariners' two years ago.
Persons:
Jason Cummings, Nick Montgomery's, Cummings, Montgomery, We'll, I've, Michael Church, Robert Birsel
Organizations:
Central Coast Mariners, Australia, League, Melbourne City, Parramatta, Mariners, Dundee, Thomson
Locations:
Scottish, Central Coast, Australia, Montgomery