Spike is dead. He's dust so there's no way he could be in it. Unless flashbacks but they'd have to do de-aging VFX on him and Angel too. I don't think tv shows have the budget for it.
"They will get to explore the world, go on adventures, meet its fascinating characters, learn new skills, collect and share resources, all whilst building new bonds that grow and evolve over time."
Heard it a million times before. Let's see if they deliver where so many others failed to.
Massacher's comments