NOT ALL sceneries are available at the moment. It's mostly the major "area" sceneries.
The move to P3d V4 is a combination of copying what you already have on P3d V3 and downloading new files. So it does go reasonably quickly, but the more you have, the longer it'll take. Buy a magazine, instead of a book.
Other sceneries, such as airports will come lately.
It's not all there yet, but it'll get there.
