Im not 100%
But i did post this somewhere else....i seem to recall the writers sayign somethign about the next season being a different timeline....But you wont know where or when....until obviously a mind blowing finale i would of thought..
Then back to island for the next season
PS...Not really a spoiler....as i cant remember if this is accurate...or i dreamt it!! HAHA

it wasnt a dream cause i read that too....unless we somehow are having the same dreams >_>
apparently the writers are really going to mess with our minds and screw around different timelines.....they say you wont be able to judge a flashback from the present or a flashforward...
also heard that a certain person will be getting a well deserve episode about their story...but the person is already dead and its not going to be a flashback???