ABU DHABI, United Arab Emirates -- In many ways, Sunday's Abu Dhabi Grand Prix felt like the end of an era. Up and down the grid there were a number of significant departures and farewells, all of which will give the sport a different feel when it reconvenes after the winter for pre-season testing next February.

The biggest gap on the 2019 grid will be the one left by Fernando Alonso. After 18 years racing in F1, the Abu Dhabi Grand Prix was his 312th and final start. Watching him chase down the final point on offer on Sunday night without success, it was all too obvious why he is bringing his F1 career to a premature end. The official line is that he no longer enjoys the style of racing F1 has to offer, but it's hard to believe he would be leaving had he been fighting for victory on Sunday.

The two-time world champion will now leave to continue his pursuit of the Indy 500 and motorsports' unofficial triple crown, but there was an overwhelming sense that F1 has not seen the last of him. Throughout the weekend he dropped hints that he would return in some way or form in the future, possibly as early as test in 2019. When a driver retires at the peak of his powers, there is always a question left hanging as to whether it was the right decision and it followed Alonso around like a cloud in Abu Dhabi.

"Right now I'm not thinking to come back, that's for sure," Alonso said on Sunday night. "But I don't know how I will feel next year. I feel I need a break now, in 2019, I need different challenges. I want to fight for the triple crown, the Indy 500 and other iconic races -- maybe Daytona, maybe other things will come.

"But yeah, for 2020, maybe I feel the need to do a full calendar in something. Maybe full IndyCar, maybe full Formula One, I don't know. Maybe that's the time to come back, or maybe I will enjoy next year so much that I will not come back."

Hamilton and Alonso spent one year as teammates in 2007, a season which will go down as one of the best in terms of intra-team rivalries in the history of F1. Lars Baron/Getty Images

Elsewhere on the grid, there will be some significant driver changes next year. Daniel Ricciardo will head from Red Bull to Renault, moving to a team that has the potential to be strong but one that still has a long way to go. He just missed out on a podium in Abu Dhabi on Sunday, and based on Renault's performance this year, it may be some time before he tastes champagne from his shoe again.

"I don't know, the initial thoughts are just ... I would have loved the podium, so I can't be ecstatic with fourth," he said. "But as a whole the time here [at Red Bull] was good, some amazing memories and a lot of things I'm sure I'll reflect on in a few hours.

"We close this chapter now, so thanks to Red Bull and the whole Red Bull family. I would have loved to have drank out of my shoe, but we'll see."

And then there's Kimi Raikkonen. The enigmatic Finn leaves Ferrari at the age of 39 in order to head back to the place where he started his career, Sauber, for another two years of racing. His Abu Dhabi Grand Prix ended when an electrical issue brought his car to a halt on the start-finish straight, resulting in his second stint at Ferrari ending in underwhelming fashion. But, as has often been the case this year, Raikkonen left the circuit with an uncharacteristic smile on his face.

Asked whether he is enjoying his racing more than ever, Raikkonen said: "Maybe I just care less -- that's a better way to put it! Obviously, when we do well, everybody enjoys more than when things are not going as we want.

"Next year will, for sure, be interesting and I'm looking to do something different. That's what I'm looking for -- we'll start testing on Tuesday [with Sauber] and then we'll see how it goes."

Raikkonen's second spell for Ferrari wasn't as successful as his first, winning just one race between 2014 and 2018. Octane/Action Plus via Getty mages

Further down the grid, there are some less happy tales to tell. Esteban Ocon will spend a year on the sidelines as Mercedes' test driver after failing to find a drive for 2019. A return is likely in 2020, but for a driver who has always shown impressive pace and rarely made big errors, missing a full season at this stage of his career will be a hard pill to swallow.

Drivers who are less likely to make a return to F1 include Marcus Ericsson, Stoffel Vandoorne and Sergey Sirotkin -- all of which have been replaced by their teams for 2019. Meanwhile, it looks unlikely that Brendon Hartley will be retained for another season with Toro Rosso after scoring just four points to the impressive 29 of teammate Pierre Gasly, who heads to Red Bull next year.

But for all the changes in 2019, it's hard to imagine any of them unsettling the man currently sitting at the top of the sport. Lewis Hamilton is going nowhere next year and -- based on his performances in the second half of 2018 -- his success story with Mercedes still has plenty of chapters left to run.

And in that respect, the race in Abu Dhabi had a familiar theme that echoed the season it brought to an end. Hamilton once again dominated from the front, while Sebastian Vettel's best efforts weren't good enough to get close enough to challenge. Valtteri Bottas hung on to his teammate's coattails for two-thirds of the race but fell away when it mattered towards the finish, and Max Verstappen made an awful start but came through the field to secure a strong finish, providing the best overtakes for the highlights reel along the way.

The top three finishers pose on the podium at the final race of the season in Abu Dhabi. ANDREJ ISAKOVIC/AFP/Getty Images

F1 needs a challenge to Hamilton in 2019, whether it be from Ferrari with the promising Charles Leclerc coming on board or Red Bull's new partnership with Honda. But hearing Hamilton speak after securing his 11th pole position of the season on Saturday night, it is going to take something special to topple Mercedes.

"On Friday I was sitting just talking to a couple of individuals who are not usually here but are up-to-date with next year's car," Hamilton said. "So we sit and have this in-depth conversation and it's inspiring... they are so smart, incredibly intelligent and they think on a completely different wavelength to the normal person.

"Ultimately I want to make sure, through our debriefs, they've not misinterpreted something. For example, I know what I need in this car to make it faster and I've got to make sure that I communicate that with them so that they go and build and find that performance. And for next year's car, I have an idea, for example, where the weak spot will be with these new rule changes, as do they, so we are just working closely and we're all of us constantly working so closely together, really elevating each other.

"I think this year, if you look at the team's performance on the race weekend, that our mechanics, our engineers, strategists, we've all raised our game. We've been better than ... you know it's never ever been perfect, neither of us as drivers ... but collectively, as a team, I think we've really continued to elevate ourselves which is again, inspiring for me and that encourages me to go out there and not want to let them down.

"So I'm confident: As long as Mercedes don't change their approach, don't change their desire to win, I believe that we'll be able to stay on this path and continue to fight at the top."

It may feel like the end of an era elsewhere on the grid, but there are no signs that Hamilton will end his time at the front of the grid anytime soon.