You don't have to play any more of EA if you don't want to, of course, but they do have a mechanism for you to choose which EA patch version you play, so you can continue playing old saves.
I expect the state management of the game/saves will probably change markedly between major patches, and it would probably be quite wasteful of time and resource to create state migration code to move saves between two arbitrary patch levels.
Maybe you can wait to start another game until a new class is available from a future patch, giving a reason to go through it again ( I have run through the EA content to varying degrees with about 5 or 6 characters, so I understand not necessarily wanting to do the same thing ad infinitum! ).