We currently have three drivers on the grid who have one WDC to their name: Kimi, Hamilton and Button. Who do you think will be the first to become world champion for a second time?
By the way: The last time that a driver won his second title and it was not a back-to-back title (i.e., a direct title defense) was Senna in 1990! Since then we've only had one-time champions (Mansell, Hill, Villeneuve, Räikkönen, Hamilton, Button), back-to-back champions (Schumacher, Hakkinen, Alonso, Vettel) or drivers who won the title for a third time or more (Prost, Schumacher).