Teams could apply for the 12th slot in 2015 until January. The FIA will decide until 28th February who will be the 12th team.
There were rumours about a new US team, but I heard they want to buy Lotus or Sauber, not founding a new team.
I think there will be no team who will be selected. ART perhaps when the budget cap will really happen but I think there will be no new team in 2015, unfortunately