Everyone knew blizzards way of doing things. When they announced a game, it is certain to take 2-3years to officially launch it. From what it seems, the jobs in d2 shud retain except for necro which might be replace with witch doctor. Luckily they didnt made it totally 3D like hellgate(the failed project of d3). Trailers shows the game pretty promising and most probably when it launches, it will be a total difference from the trailer itself.