No, he's not dead. In fact, if you look at the times we've used the spell in the past with Klaus and Alaric and Esther and Rebekah the magic is the same. So if and when Klaus vacates Tyler's body, Tyler will still be there.
The first episode is a lot of people feeling a lot of guilt, a lot of torment and Elena having to manage all of that in the midst of realizing she has a big decision to make. Obviously Stefan knew he was going to come right back for Elena, but she ran out of time. That is a decision that's going to haunt him and infuriate Damon, but probably lead Elena to explain even more to Stefan why she chose him because of that.
This could drive a pretty severe wedge between the brothers. Certainly the intention is not to subtly and forcefully rip them apart; it's more that they're going to have different points of view. It's going to bring back a lot of the issues about Damon when he came to Mystic Falls and what he expected his vampire life to be. They're just not going to agree. It's going to be frustrating for both of them, and even though they're in it together, they're coming at it from different sides.
It was meant to illuminate that we don't have all the information and neither does Elena. She's made her decision and she believes in that decision wholeheartedly based on who she is in her life and what she knows, and now she's going to wake up and be a completely different person and have all this new information. Do I think it's going to immediately make her say, "Oh, I've chosen wrong?" No, but it's yet another thing that's going to be in her head confusing her about her feelings.
The transition of it all will take place in the first episode. There's a nice 24-hour window there and that will be particularly dramatic and traumatic. Looking past that, all I can say is if Elena becomes a vampire, if you really think about who she is and what we've seen in her, she's fiercely protective, she spent a lot of time in this last season getting physically stronger, her compassion is her greatest gift and her greatest weakness, so in death that becomes magnified.
Bonnie's first thing that's going to have to happen is that we're going to learn how long she has to keep this secret, what kind of bargain she made with Klaus, is she going to be able to tell her friends, specifically Caroline, right away? As a witch who can be looked at for solution, trying to figure out a way to keep Elena from having to be a vampire is going to be high on her priority list and she's going to have a very limited amount of time to do it. In the first episode, we'll see Bonnie step right up to the precipice of the darkest form of her magic and need to either jump on in or stay back on the ledge.
She's just been completely bamboozled and experienced the most horrifying and devastating moment of her entire life, so realizing that it wasn't real and that all of those painful goodbyes were not Tyler but were with Klaus, that's going to be a low blow.
I loved a line where after Alaric confronts Meredith, he's walking out the door he looks back at her and says, "Too bad, you and me, it was kind of love at first sight, wasn't it?" I loved it, but ultimately the story was told just fine without it.