According to Joe Saward, Williams & Toro Rosso will be changing to Mercedes & Renault respectively.
http://joesaward.wordpress.com/2013/05/24/williams-to-mercedes/
As well as this, Marussia seem to have Ferrari engines for next year, and of course Mclaren will stay with Mercedes for the final year of their partnership.
http://joesaward.wordpress.com/2013/05/24/williams-to-mercedes/
As well as this, Marussia seem to have Ferrari engines for next year, and of course Mclaren will stay with Mercedes for the final year of their partnership.