Hamilton and Vettel are locked in a fierce battle for the top prize this year, which the Brit is leading by 30 points.
The pair are preparing for the next episode of their rivalry at the Singapore Grand Prix this afternoon.
But for Ricciardo, his attention has already switched to next season after agreeing to swap Red Bull for Renault at the end of the campaign.
The Australian shocked the Formula One world when he announced his departure from Christian Horner’s team – but he claims it was because Ferrari and Mercedes are streets ahead of their rivals.
“I really see it hard at the moment for anyone to fight for a title other than Ferrari and Mercedes in the next 12 months,” Ricciardo told Sky Sports.
“Obviously Red Bull are an unknown now with Honda, but still the odds are with Ferrari and Mercedes.”
Ricciardo will join Renault, who are fourth in the Constructors’ Championship, for the 2019 season.
But he is not expecting to perform his infamous ‘shoey’ celebration until at least the following year.
“I think it’s realistic to think a podium ‘shoey’ could come in 2020,” he added.
“I don’t want to count off a podium next year but I think realistically it has to come under some circumstances, if it’s a bit of a crazy race like Baku 2016 or something.
“I think it’s going to take another 12 months to be a podium contender but that’s the trajectory they’re on.
“I kind of feel like 2019 is going to be a building year, regardless of where I was going to be, so we’ll try and do what we can next year but attack in 2020.”
Ricciardo will start the Singapore GP from sixth position after Red Bull once again struggled with their Renault engines during qualifying.
The Austrian team are swapping suppliers to Honda from next year, but that was another reason why Ricciardo has chosen to leave.