As 2015 season ends, is the sun setting on Formula One?

Nico Rosberg's victory in Sunday's season-closing Abu Dhabi Grand Prix may not install him as favourite to unseat his Mercedes team-mate Lewis Hamilton, but it has given the three-time champion much to ponder ahead of the 2016 season.

After three straight wins, the 30-year-old German has rebuilt his confidence and the confidence of the Mercedes team in him while Hamilton, who won his second successive title with Mercedes a month ago, appears to have struggled to find the motivation to resist his team-mate's late-season vim.

But, as Formula One heads home for a winter of rest and reorganisation, it is the sport itself that faces the biggest challenge next year with several teams struggling to cope with the huge costs, uncertainty surrounding the number of entries and no clear sense of direction for the future.

Two-time champion Fernando Alonso's post-race rant at the inconsistency – and ineffectiveness – of the sport's ruling body, the International Motoring Federation (FIA), summed up his season and the views of many after a year in which his team McLaren-Honda endured endless failings and disappointments.

“It's FIA things,” said Alonso. “We see the grandstands half empty on this circuit – and half empty on most circuits ... And there are championships, which are overtaking us on the right, like WEC, MotoGP ... And then we are trying to make the cars louder! I think we need a bit of common sense.”

Embroiled in financial, political and technical problems, the season ended on Sunday with few signals that a brighter future lies ahead. Earlier in the week, former FIA president Max Mosley told the BBC that F1 was in serious trouble and nobody wanted to buy the business because it had become too expensive.