Full translation of Nomura's comment on part 2.
As others have noted, Nomura specifically says part 2 will pick up after Intergrade, which has some people speculating that this expansion might push the story further than departing Midgar. I wouldn't be surprised to see some new post-credit scene.
This translation also says that Cloud will generally be around nature more in part 2, not that it'll open in the wilderness, so a Nibelheim flashback opener is still on the table. Otherwise I could see part 2 opening with the party being chased by Shinra in the fields between Midgar and Kalm. Would make for a good action piece that teaches whatever new party mechanics are implemented. Then they hide out in Kalm.