The Welshman, who won last year’s race, believes Chris Froome will be chasing a record-equalling fifth title alongside this year’s champion Egan Bernal.
“If all three of us are there on the start line, jeez, we’re going to have questions about leadership,” he said.
“But other teams will have to answer those questions on the road. It will be great to have that strength next year.”
Thomas, Froome and Bernal all lined up for for Team Sky (who were taken over by Ineos earlier this year) at the 2018 race, with the latter riding as a domestique for his more experienced team-mates.
The 22-year-old Colombian showed his potential by pacing Thomas to victory on Alpe d’Huez and ultimately the overall title, prompting Froome to say: “There is a lot in Egan that reminds me of myself when I was younger. It’s great having him on the team and he brings a lot of young, new energy to the group.”
Froome, who missed this year’s Tour after suffering a broken neck, femur, elbow, hip and ribs in an accident at the Criterium du Dauphine on 12 June, is ahead of schedule in his recovery, according to team boss Dave Brailsford.
Brailsford said: “In typical Chris Froome fashion, he’s putting everything into his recovery.
“Hopefully we’ll see him back at the Tour de France next year.”
Froome is one of seven riders to have won all three Grand Tour titles and his haul of seven includes two Vueltas a Espana and one Giro d’Italia title.
“You know what he’s like,” Thomas said of the 34-year-old. “When he’s not on his bike, all his attention has shifted to his rehab and it’s remarkable to see how quickly he’s improved. Hopefully I’ll get a chance to go and see him and catch up soon.”
Thomas arrived at this year’s Tour as the defending champion but had to settle for second place behind Bernal.
“To finish second behind a team-mate makes it OK,” said the 33-year-old Welshman.
“Two years ago I had my arm in a sling with a broken collarbone watching Froome win, wishing I was riding and I would’ve taken second then, but it just shows how time and expectations have moved on.”
His own preparations for the Tour were disrupted by a race-ending crash at June’s Tour de Suisse and he had three more minor spills during the three-week race around France.
However, he said anyone suggesting he might be beyond winning a second Tour only inspires him.
“I don’t read it, although certain stuff filters through to me and it spurs me on,” he said.
“I’m a lot closer to the end than the start: Me and Egan are on separate spectrums, but it’s great to be having this success.
“I’ve had my Olympic success and it’s pleasing to have some more on the Tour de France.”