You have general contractors and then you have subs that work under them. A general contractor is a jack of all trades, master of none. Exactly what a full stack developer is.
This isn't the end of specialization. It's the beginning of project management steered by developers who intimately understand all of the work involved, even if they aren't as competent as the specialists.
Having a team consist of all full-stack developers is just stupid. Having a full-stack developer as the head on a project, with specialists on the team, is a great idea.