I definitely don't think they'd get away with killing off Luanne and Lucky. I think the sting of an orphaned Gracie would be a bit much. My own feelings are that Luanne and her family will be referenced as offscreen in phone calls, etc., where we get infrequent updates through Peggy or Bobby, and eventually the characters are seldom, if ever, mentioned again until the eventual revival finale.
Or maybe they'll recast them, who knows.
The actual teaser video here really catches me off guard. Hank pressing himself against the glass feels out of character. Peggy's suicide remark feels more harsh than it was probably meant to be. The animation style. I'm happy to get more of the Hills, but I can tell this is going to take some getting used to for me.