What's next for Fernando Alonso?

It only took 13 years, but Fernando Alonso finally claimed a third world championship at the weekend.

It wasn't the F1 title he so desperately craves, but the World Endurance Championship -- the pinnacle of sports car racing -- with the dominant Toyota team, capped off in style with a second career victory at the prestigious Le Mans 24 Hours.

Alonso has no desire to return to F1 any time soon, at least until he has a chance of winning a third championship there. He also will not immediately return to WEC, saying on Sunday "I want to be a little bit more open for my options for next year". He certainly won't be short on those and now has plenty of time to weigh them all up.

Here's a look at the most obvious, and the more left-field, available to him.

Indy 500, Part III

Alonso's second Le Mans victory will have only fueled his desire to return to Indianapolis. He already had two-thirds of the Triple Crown, but it seemed like a fitting way to cap off his successful season with Toyota -- while he is yet to win at the Brickyard, he now has two wins apiece at Monaco (2006 and 2007) and at Le Mans (2018 and 2019).

Alonso and McLaren's second attempt at the Indy 500 this year ended in pitiful circumstances in May. The Spaniard failed to qualify for the event after a string of remarkable blunders by his team, including a test delayed because the team did not have a steering wheel and complications around the spare car being painted the wrong shade of orange.

The whole saga raised questions about McLaren's preparations, although CEO Zak Brown has ruled out his team joining IndyCar full time in 2020. It seems more likely the team will attempt to enter Alonso in additional races early next year in order to better prepare him and the team for the Indy 500.

McLaren has already paved the way for an easier return -- Andreas Seidl has finally started as boss of the F1 team, freeing up former Indy 500 winner Gil de Ferran (now McLaren's sporting director) to take a more hands-on approach to any future involvement in the race, as he did ahead of Alonso's debut there in 2017. Brown has already admitted De Ferran was not involved enough this time around.

Regardless of McLaren's readiness, the Indy 500 will be the toughest challenge of Alonso's career so far, such is the randomness of the outcome and the difficulty drivers of every calibre have of winning. But there is no doubt he will be back and, despite the failure of May this year, it seems unlikely he would make his third attempt to win the Borg-Warner Trophy without the backing of McLaren.

However, he refused to commit to anything after this year's failure.

"Right now I think it's difficult to make any promise," Alonso said. "It's just too soon to make decisions.

"I don't know even what I will do after the Le Mans 24 hours, finish my program in the World Endurance Championship, and I wanted to have 2020 open because I don't know exactly what opportunities may come for me for next year in terms of racing.

"So, I don't know -- until I know the program for next year, I cannot promise or have any idea in my mind. But as I always say, I would be more than happy to race here again in the future and to win the Triple Crown, which is still a target."

So what else could fill Alonso's 2020 calendar?

Formula E? Rally?

Formula E founder Alejandro Agag has made little secret of his desire to get Alonso to race an all-electric car one day. Agag admitted the series' 2019-20 campaign was most likely, mindful of him wrapping up his WEC duties with Toyota, although his fellow Spaniard has always seemed fairly lukewarm to the idea.

Formula E is ambitious enough to lure Alonso over. The series is rapidly developing its race cars -- drivers are no longer required to swap vehicles midway through each event, for example, and its 'Generation 2' car is clearly a big step up on its predecessor. Whether or not Alonso sees it as a challenge he needs to take on remains to be seen, especially given the wealth of other options which would be open to him.

Alonso previously teased some form of NASCAR involvement with series legend Jimmie Johnson. The pair swapped cars at an event in Bahrain last November, with Alonso getting time behind the wheel of Johnson's Hendrick Motorsports Chevrolet.

Earlier this year, David Wilson, the head of Toyota's U.S. racing arm, hinted at a desire to get Alonso involved in a NASCAR road course race in future. Wilson's quotes were very revealing about Alonso's current mindset.

"He's looking at the entire horizon -- I don't think there's anything that's not a possibility for Fernando," he said. "Who knows?

"Putting him behind the wheel of a road course race, at Sonoma or Watkins Glen, that would be fun. "I don't know if it's possible, but he'd be very interested - absolutely. It would be great for business."

Brown has also been trying to coax Alonso to try a proper race in the series, saying after the Bahrain test: "He's not agreeing to it yet, but I am going to work on him a little longer. He is mega quick and has also never driven anything like it, so I think it shows when you have got world champion drivers and give them a steering wheel and give them a race car, then it doesn't take long for them to get up to speed."

Beyond his foray into IndyCar machinery and sports cars, Alonso also got his first test of a rally car last year. He sampled Toyota's Dakar Rally winning car at a test in the Kalahari Desert in March, an experienced he labelled "incredible".

Next year's Dakar Rally will take place in early January, a month which also includes the 24 Hours of Daytona, which Alonso has competed in for two straight years.

Road map back to F1

Hanging over all this should be the proviso that Alonso never officially retired from F1. Brown has left the door open for his return, but that outcome seems unlikely until McLaren returns to competitiveness. While the orange car has clearly improved this year, F1's imbalanced pecking order appears to be locked in until the new regulations for 2021.

Recently, rumours have circulated that Sebastian Vettel is considering retirement at the end of 2019, a belief only strengthened by his demeanour after being controversially denied a win at the Canadian Grand Prix. Of course, an F1 rumour like that wouldn't be complete without the suggestion Alonso could fill any seat made vacant at Ferrari, which has appeared in several media outlets recently. While Charles Leclerc appears to be the team's long-term future, there is no doubt it will have been assessing its options in the case of Vettel calling it a day later this year and Alonso is about as perfect a short-term option as you could find on the driver market right now.

Alonso would surely be tempted by that sort of opportunity.

Earlier this year, the two-time F1 champion said: "I achieved a lot more in F1 than I dreamed of and I had great opportunities outside F1 to do something unprecedented. That's why I took the decision.

"So coming back is not in the plan. If something happened and a great opportunity arrives, I probably will consider [it]. I don't close doors 100 percent to anything in the future."

Alonso back in a competitive F1 car is a tantalising prospect, but it remains the most unlikely for the time being. While he would still be racing in F1 if he was in a position to win races and titles he seems to have been reinvigorated by his current stint away from the series.

At the moment, anything and everything seems to be on the table -- so watch this space.