This means a considerably longer game, with previously closed-off areas of the game now available to explore in an open-world fashion, with more side-quests, new enemies and new content in the game. This has also meant splitting the game into multiple parts for release. Part I is expected to include at least the opening part of the game, set in the city of Midgar. In the original game the Midgar episode took roughly 5-6 hours to complete, but the Remake version sounds like it may last for several times that amount.
More information will be released on the game in the next few days, including hopefully more information on the release schedule for the remaining parts.
The game will initially be released on PlayStation 4, with X-Box One and PC versions of the game likely to follow (based on Final Fantasy XV, probably within 18 months of the original release).