I think that Cora must be alive & that Regina must have cursed her really badly (or at least tried to); because when Regina “saved” Charming from been executed by King George, she said something about making him suffer instead of giving him a quick death.
What I am VERY curious about from the promo are the scenes of a very young looking Regina with 2 unknown guys. I think one of them looks like Jefferson & the other seems to be carrying some kind of doctor bag or something. I read from another post that some people think that the other guy may be Dr. Frankenstein because of the scene with a tent & lightning striking or something. The guys also appear with Rumple in another shot. There’s also a scene of Regina kissing Daniel in the promo, so maybe Dr. Frankenstein’s trying to revive him… I am SO looking forward for the Regina/Cora episode(s)!!!