The race has been a part of the sport since the birth of the world championship in 1950, with Monza a mecca for motor sport fans.
Only once has the fabled venue failed to stage the race, in 1980 when it was switched to Imola, but it may now be axed altogether once the present agreement expires in 2016.
"It's not good," Ecclestone said when asked by Italian newspaper Gazzetta dello Sport about the future of the race. "I don't think we'll do another contract as the old one has been disastrous for us from a commercial point of view, so it's bye-bye after 2016."
Ferrari's circuit at Mugello has been mooted as a likely replacement, although Ecclestone claims he has not yet received any proposal. One key factor behind the race's potential departure is an alarming drop in F1's TV audience in Italy, with Ferrari's lack of form not helping.
"TV ratings are lower in Italy than elsewhere," Ecclestone added. "Channels have split with digital broadcasting, and there's also Twitter, Facebook and other communication means, so young people are more distracted.
"How to improve Italian ratings? If Ferrari started to end up first and second in qualifying and races, TV ratings would improve everywhere. Ferrari is a worldwide passion."
Meanwhile, Christian Horner, the Red Bull team principal, has praised Sebastian Vettel for his reaction to the team's ongoing crisis. Following an abysmal Austrian Grand Prix, Horner slated power-unit supplier Renault for their performance, describing it as unacceptable.
After suffering an electrical fault on lap two which almost resulted in Vettel grinding to a halt - he got going again but dropped to the back of the pack - Red Bull opted to retire their four-time world champion after 34 laps to save the car. It was the third time this year Vettel has been forced from a race, as many as incurred in the previous three years combined.
"He's been remarkably mature about it, to be honest with you," said Horner. "He's not been shallow in any way, he's not spat out his dummy or thrown the toys out, and he's had the majority of the problems this year."