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Bolt, who completed a sprint double in Beijing with Thursday's 200m win, added he would run at the 2016 Olympics.
"I want to run but I think the sport is not as fun as it used to be - it's more taxing," the 29-year-old, who has won 10 world titles, told the BBC.
"I can't enjoy it as much as I want to because I have to sacrifice more."
He added: "It is 50-50."
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Bolt could make his gold-medal tally to 11 this weekend when he competes for Jamaica in the 4x100m relay.
Once again he is likely to face Justin Gatlin in the final, with the United States one of the favourites for gold. The Jamaicans were beaten by an American quartet at the IAAF World Relays in May.
"In the World Relays, Justin Gatlin had a big game in their victory," added Bolt. "I guess he will be tired now. There will be no reason why we should not win the relay."
Some media outlets have been accused of portraying Gatlin as the "villain" to Bolt's "hero" following two career doping bans.
He came into the World Championships having set the best times over 100m and 200m this season.
Bolt pipped Gatlin to the 100m title, before the American fell to a more emphatic defeat in the longer sprint on Thursday.
Asked by BBC Radio 5 live if a double silver was a disappointment, Gatlin said: "Not at all. I'm out here competing. I'm aged 33.
"I think a lot of people now see the hard work and effort I put into it. It's not a personal race, it's also for my country.
"In the 100m, I beat myself. In the 200m, technically I ran to the best of my ability."
When asked about the media's portrayal of him in the lead up to Beijing 2015, Gatlin said: "I go into shutdown mode. I don't worry about what the media has to say.
"You guys do your job, sensationalise stories sometimes. My job is to compete and get to the line."

Jose Cuervo has taken control of the brand as part of a deal with Diageo.
Diageo's Colin O'Brien said while the sale represented a "change", they were "confident" that Jose Cuervo would "nurture" Bushmills in the future.
Jose Cuervo is owned by the Mexico-based Beckmann family. Their distribution firm, Proximo, controls a number of premium whiskey and rum brands.
The chief executive of Jose Cuervo, Juan Domingo Beckmann, described the acquisition as the "most important purchase made by Cuervo in its entire history".
"Like Bushmills Irish Whiskey, Jose Cuervo is built on a very strong tradition of quality and craftsmanship that dates back over 250 years, so we understand the importance of nurturing and protecting the heritage and quality of a brand and are strongly committed to doing exactly that with Bushmills," he said.
"Bushmills Irish Whiskey will be in very safe hands."
Mr Beckmann added that no jobs would be lost at Bushmills as a result of the acquisition.
Mr O'Brien said Bushmills Irish Whiskey was a brand built on "great history, heritage and passionate people" and had been a "cherished part of the Diageo family" for more than nine years.
"During this time we have invested over Â£80m to build capacity, infrastructure and maturing inventory at the distillery, which has supported the continued growth of the brand," he said.
Irish whiskey has been a growth category in the United States in recent years.
Growth was initially sparked by a big investment made by Pernod Ricard in the marketing of its Jameson brand.
In 2011, the US-based maker of Jim Beam whiskey bought the Cooley distillery in County Louth for $95m (Â£59.45m).
Bushmills Distillery claims to be the oldest licensed distillery in the world.
Distillation has taken place there since at least the 17th century.
It has not been locally-owned for many years.
Prior to being bought by Diageo in 2005 it was owned by Pernod Ricard.
Jamaica's Usain Bolt says he is "50-50" to compete at the 2017 World Championships in London because athletics is less enjoyable for him.
[NEXT_CONCEPT]
Bushmills whiskey has been acquired by the world's biggest tequila producer.