Gillespie, who retired from Australia'n side at the end of 2007-08, has made 11 appearances for Glamorgan this summer in between injuries, taking 21 wickets at 34.61.
Gillespie is set to be replaced as the county"s overseas player by Herschelle Gibbs next season, although the paceman has offered his services on a temporary basis if the South African is on international duty.
"It is probably going to be my last couple of weeks in first-class cricket," said Gillespie.
'If it is going to be my swansong, I am pretty content with that.
"It is not set in stone, but that is the way I am leaning at the moment."