Although the world championship has gone down to the wire, it is stacked in Fernando Alonso’s favour. The only chance Michael Schumacher has is to win today’s Brazilian Grand Prix, with Alonso failing to score a point. It is difficult to envisage that, although there was an early scare for the Spaniard when his Renault team had to change his engine on Friday before practice had begun. No grid penalty applied, but it was a bad omen.

I have been hearing all sorts of conspiracy theories from fans and friends, many of them convinced that there will be some skulduggery afoot to ensure that Alonso is torpedoed. One guy even asked me how much money I thought Ferrari would be paying Michael’s teammate, Felipe Massa, to take Alonso out. It is crazy talk. That is simply not happening. It would be incredibly damaging for the sport if anything occurred that could be interpreted in that way.

Any other driver winning would secure it for Alonso and Renault. A Kimi Raikkonen victory for McLaren, Alonso’s future employer, would do nicely, and McLaren are hardly best of friends with Ferrari. Jenson Button also looks handy for Honda.

Ferrari have possible support from Red Bull, to whom they supply engines, but their lack of pace will keep them out of the action among the frontrunners. Curiously, BMW have chosen to send farewell messages on their race cars to Schumacher, a fellow German. Let’s hope Alonso doesn’t trip over one of them, otherwise those conspiracy theorists will have a field day.

Alonso’s approach this weekend has to be “business as usual”. I am sure they will turn the power of his engine down a little bit, to be on the safe side, but other than that I would expect Renault to attack as they always do. Alonso’s teammate, Giancarlo Fisichella, a former winner here, could help out nicely too.

Although there is a widespread feeling of support for Alonso in the paddock, most of the fans seem to be supporting Schumacher, feeling that for him to leave the sport with an eighth championship would be an appropriate fairy-tale end to the story.

It is not only Schumacher who is leaving Formula One after this weekend. Cosworth — the legendary engine supplier that has graced the grids since 1967 — is taking part in its last grand prix, at least for the time being, as it has no F1 customers for next year. The regulation engine specification freeze will have a profound effect on the structure of the teams. One leading team boss told me that he expects his engine personnel to drop from 300 to maybe as few as 100 next year.

This is also the last race in which we will see a tyre war, with Michelin pulling out, leaving Bridgestone as the sole supplier. I think F1 will lose a lot because of that.

My colleague Hugh McIlvanney wrote in his column two weeks ago: “Bridgestone versus Michelin. It’s hardly Frazier vs Ali, is it?” While I take his point, I still think that the tyre war added a further level of intrigue, uncertainty and opportunity.

We are losing a whole layer of the structure of a race weekend. Even for Bridgestone it is a disaster, because tyres are not going to be mentioned so much. Perhaps the most significant change is the end of high-visibility tobacco advertising. Honda’s Lucky Strike and Renault’s Mild Seven sponsors have been obliged to pull out because of the ban. The first of these marketing initiatives was Gold Leaf back in 1968, meaning that for almost four decades the tobacco companies have largely funded the sport. That is coming to an end, although Marlboro are still backing Ferrari with low-key imagery on the rear wings of the cars.

I have a bit of a guilt complex about tobacco sponsorship, because almost every racing car I drove professionally had it. You kid yourself and say: “Well, if I didn’t drive it, someone else would have.” Over the years it has brought a shedload of money to the sport. The manufacturers have increased their investment to compensate, and other sponsors are beginning to come in.

It is the last time we will see Alonso in a Renault, the last time we will see Raikkonen in a McLaren. The Kimi/McLaren partnership has not really delivered what it promised. And this season we have “lost” Juan Pablo Montoya and Jacques Villeneuve. Even as the title celebrations are in full swing tonight, F1 will be looking forward — to a post-Schumacher, post-tobacco but exciting future.