[Sohcahtoa82]

This is correct.

The game client is about a 91 gigabyte download which will include all the aircraft and a low-resolution copy of the entire world. This offline data is fully functional.

You only need to be online for multiplayer, live air traffic data, and to stream high-quality versions of the world.

Also, the game has an option to manually add areas of the world to the high quality data cache, so if you know you're going to be without Internet for a while, but still want to be able to fly over certain areas with high-quality imagery, you can do that.

[Voliokis]

Isn't there an online check to ensure you have a license?

[Sohcahtoa82]

I would hope that if the game servers were being taken offline permanently, then the license check would be removed.

Even if Microsoft chose not to remove the license check, it would certainly get cracked. Cracks likely exist already.