Nico Rosberg's future plans remain unchanged as he focusses on improving Mercedes

With Button, Fernando Alonso and Sebastian Vettel now all tied up with their teams for the foreseeable future, Rosberg is one of the leading drivers who are free agents for 2013 - when there could be vacant seats at both Red Bull Racing and Ferrari.

But despite the good position he finds himself in, Rosberg says that he is still focusing at the moment on building a stronger future at Mercedes GP.

"I don't really want to speak about the long term," he said, when asked by AUTOSPORT about the implications of Button committing himself to McLaren for the next few years.

"All I can say is that I am very, very happy here, and it is great to see the direction this team has taken. I believe this team is going to make it, so that is all for now."

Rosberg is hugely encouraged by the restructuring that has gone on at Mercedes GP this year, allied to the signing of Aldo Costa and Geoff Willis to boost its technical strength.

And he dropped a firm hint that although there may be good options elsewhere to consider for 2013 - with Ferrari and Red Bull Racing believed to consider the German a possibility - that a future at Mercedes GP could be right option for him anyway.

"It might still take a while, but eventually it is the best position to be in," he said.