I think Seb's time is probably up. He needed to perform better this season - there's no shame in being beaten by Vettel, but Buemi is a rookie and wasn't even the best of an average crop in GP2 last year. So I'm not convinced that Buemi's a future superstar, by any means.
Why hasn't it worked out for Seb? Well, unlike previous ChampCar champions (Villeneuve, Zanardi, Montoya) he won his titles when many of the top teams - Ganassi, Penske, Green - had defected to the IRL. The only two really well-resourced teams were Newman-Haas, who he was driving for, and Forsythe, who had Paul Tracy, not the finest driver of his generation, nor the most subtle, and at that time already somewhat past his best. Nevertheless Timo Glock was in ChampCar at the same time, and it evidently didn't do him much harm.
Perhaps it's just a question of horses for courses? Everyone who saw Jan Magnussen in the junior ranks thought he would be a success in F1. Same goes for Antonio Pizzonia to a lesser extent. Sometimes a particular car or type of car doesn't suit a driver's style, and if they are unable or unwilling to modify their approach there's little that can be done. When they brought in the narrower track F1 cars with grooved tyres in 1998, Villeneuve and Hill struggled mightily to come to terms with the new handling balance (some might argue that they never adapted fully).
Still I'm surprised that Alguersuari seems to be the name in the frame to replace him. He came out on top of a very close battle in British F3 last season with fellow Red Bull Junior Brendon Hartley, Cambridge graduate Oliver Turvey (supported by the Racing Steps Foundation) and Sergio Perez (supported by Mexican telecoms billionaire Carlos Slim!).
This season however, in the Renault World Series he has generally been outpaced by team-mate Turvey. It's a big move up for him after only six months in a high-powered single-seater (particularly as his best result in the aforementioned high-powered car is a fifth place).
