http://www.swtor.com/community/showthread.php?p=8255401
As a subscriber, when you get Fallen Empire you will receive one free level 60 character. This character must be a new character, you cannot “boost” an existing character up to 60. Beyond that first one which is included free with KOTFE, you can purchase additional level 60 characters through the Cartel Market at any time. I know that this raised the question of character limits as well. In talking with the development team, the plan is to increase the subscriber maximum character limit per server by 2 for the Fallen Empire launch. Not confirmation it will happen, but it is definitely their goal!