The only game that has a shot at taking FinalFantasy down from the sales champ(RPG terms) is DragonQuest but that is also owned by S-E so once you take FF down you then have DQ to take down and you can bet your money by that time S-E will be making an FF to take down the thing that took down FF.
End of 2014 Hardware Predictions (03/03/14)
PlayStation 4: 12-15million
Xbox One: 7-10 million
Wii U: 8-9 million (Changed 01/04/2014 from 7-9 --> 8-9 million)