Fernando Alonso won't win another world championship. That's not to say he doesn't have the ability to, because he does, or that he doesn't merit one, because he does, but the odds are increasingly stacked against him.
Predictions are a mug's game and time might prove this statement to be spectacularly wrong. But let's look at the overwhelming supporting evidence.
The great truism of motorsport is that to win a world championship, you first must be in a world championship-winning car. Alonso is out of contract at the end of this season, and barring some unexpected and seismic shift in the driver market, he's vanishingly unlikely to end up at any team in the top six or seven of the constructors' championship.