The 36-year-old Swiss, who holds the men's all-time record of Grand Slam titles with 20, was speaking to a small group of journalists prior to winning two Laureus awards -- 'Comeback of the Year' and 'Sportsman of the Year' -- on Tuesday.
Laureus is a global movement that uses the power of sport to tackle the most devastating social challenges in the world.
Federer, who missed the ATP tournament in Dubai this week to attend the awards, said the younger generation such as Bulgarian Grigor Dimitrov and Dominic Thiem of Austria have the ability to win a Grand Slam but 10 might be beyond them.
"It is definitely hard to see one player right now getting 10 slams," said Federer.
"It is much easier to say that probably a lot of guys are going to win a slam or two but winning 10 slams is not something you can predict, people didn't predict that with me to be honest.
"Maybe with Rafa (Nadal) with the French Open you say yes he is going to grab a few there. Maybe he is going to win five (he has 10 to his name) as he was an amazing junior as well like Bjorn Borg, they were the best teenagers we ever had in the game."
Federer, who came to Monaco on the back of winning the Rotterdam title where he beat Dimitrov in the final, admitted fortunes can change with the slightest of tweaks.
"Once you get rolling like Novak and I did all of a sudden you don't look back, then a few years later you do look back and you have eight or 10 Grand Slam titles, it's crazy," said Federer, the oldest world number one in ATP history.
"Confidence and momentum are a big thing.
"When you unlock your game through success or a coach explains the one ingredient that is missing then that can change things."
- 'A shadow over the game' -
Federer, however, believes the sport will not suffer once the likes of him, 16-time major winner Nadal, 12-time Grand Slam Djokovic, and Andy Murray finally hang up their rackets.
"The game of tennis always has a way of producing champions and the future has never worried me," he said.
"Someone will follow in our footsteps and be a champion.
"We are a shadow over the game, the top guys, and clearly we don't allow them (the younger ones) to completely flourish but once we are gone I think it will still be very, very exciting."
Federer, who says his lighter tournament schedule these days keeps him hungry and motivated, has had his fair share of injury problems in recent years, and he urged two-time Wimbledon champion Murray not to rush back to competition following hip surgery in January.
"What I learned is just be patient when you are hurt, only come back when you are 100% not 92%," said Federer, who will make up his mind about whether he plays the French Open after the Indian Wells tournament in March.
"I've come to realise it is better to wait. If you are hurt or struggling in a tournament no one knows so that is ok, but if people know you have had a problem it is better to wait it out and train really hard to get back at 100%."
Federer believes whilst part of his enormous popularity is down to the success he has enjoyed, it is also perversely to do with how he handled tougher times.
"Maybe going through tougher moments since 2010 and 2011 came around when I didn't win so much," he said.
"People saw me struggling a little bit more and they thought of me as being more human and since then my popularity has really gone up even more so since the comeback (undergoing knee surgery in 2016 and returning to win a record eighth Wimbledon crown in 2017)."