Now I have no clue if this it true but ...
"During the Sacrifice Damon will get bitten by a werewolf and what should be a tender moment between Elena and Stefan will reveal itself to be a bittersweet farewell. Stefan is going away to search for a cure for his dying brother in season 3. During the Gone With The Wind movie night in town’s square Damon’s dementia causes him to confuse his memories of 1864 Katherine with his present day feelings for Elena. A long awaited Delena moment happens when Rhett embraces Scarlett for their epic kiss and Damon passionately kisses our heroine. This time Elena doesn’t reject him and returns Damon’s advances as he collapses to the ground. Elena falls with him, kneeling there beside him, distraught and unsure."
Source This how ever i know is true.
"While Mystic Falls presents a screening of “Gone with The Wind” in the town square, Damon’s (Ian Somerhalder) memories of Katherine (Nina Dobrev) in 1864 mix with the reality of Elena (Nina Dobrev) in the present day. Stefan (Paul Wesley) pays a terrible personal price for his attempt to prevent a tragedy, and Sheriff Forbes (Marguerite MacIntyre) makes a deadly mistake while trying to keep everyone safe. More than one life hangs in the balance as the consequences of the sacrifice ritual play out to a horrifying conclusion."
Source Personally the whole with Damon's mixing of Elena today and Katherine of 1864 sounds like the werewolf thing but 'Stefan pays a terrible personal price' sound more like it might be him. I don't know, but if they kill of Damon I don't think all be able to watch anymore. THEY CAN'T KILL DAMON!!!