I think with ferraris heritage, most F1 drivers dream of driving the red car with the prancing horse on.
That almost goes without saying.
What driver wouldn't want to drive for Ferrari?
Driving for Ferrari is the equivalent of a footballer wanting to play for Manchester United, Barcelona, Real Madrid, etc. Every sportsman dreams of moving to the teams (in any sport) which have the biggest reputation/history.
Personally, I don't think he will join as I can't see him officially agreeing to drive as No.2.
McLaren
Personally, I don't know what McLaren are playing at. They firstly allowed 2 drivers in 2007, to go head to head and take points away from one another, which resulted in a title loss. They then got rid of what most believe to be the best driver in F1. They then hire a chump, who can barely scrape a top 6 finish, while their other driver wins the race. They then bring in Button (a good move), but then have no (strong) team orders in place, so that both drivers are taking points away from eachother. While all this is going on, their design team is found wanting, compared with RedBull who are basically steam rolling over them. Nothing is being changed to deal with McLaren's problem of starting out with a slow car and playing catchup for the entire season.
Ferrari
At least with Ferrari, they are putting plans in place to handle RBR. They first hired the best driver in F1. They then ensured that he got No.1 status and that Massa will support his team-leader. They have made several changes within the design team hierarchy in order to improve things, to give Alonso the best chance of winning the title. Ferrari are the team who have a better chance of moving forward, as they have at least acknowledged that changes have to be made. McLaren are just "hoping" for the best.
Hamilton
One thing I do not understand is that Hamilton believes that he must win world titles (as does Alonso). Alonso is creating a team around him and is preparing for a major fight in 2012 and onwards. Vettel is in currently the best time in F1. Hamilton on the other hand is hanging on to a team, which have a poor track record, compared with the other leading teams. If I were him, I would be fighting tooth and nail to schmooze RBR into giving him a seat for 2013 (he has missed his chance for 2012). He even acknowledges that in 2012, McLaren are likely to start behind RBR...again.