Twilight Town returns in Kingdom Hearts 3 and it serves as a level that gives you the tutorial. It will obviously be be the first stages that Sora and the gang will visit.
This was confirmed by Tetsuya Nomura himself who was interviewed by Dengeki Online (via NeoGAF). Aside from that, some other small news about Kingdom Hearts 3 was also covered in this interview.
He said he announced the 2018 release window to give people a peace of mind. People were worried not knowing the approximate date when the game was coming out.
He also confirms that more people can join the party in this game. 4 or more people and guests can join Sora in fights. This is why we saw a 5 party team in the Toy Story world.
Sadly, the Toy Story world won’t allow us to explore the streets around Andy’s house. Nomura says the main area is the Toy Shop which is “Galaxy Toys”. He said Galaxy Toys is still a very large area though.
The game has been in development for a long time, but thankfully we can finally play it next year. More news about the game should be shared in the coming months.