The world does have a end! Proof from MSFS2004...

[Hodgkinson]

Have a look at this screenshot:
http://www.booni.info/downloads/MSFSedgeofworld.jpg

According to the map in FS2004, you're at a coordinate that is invalid. By the top-down view, you're at the north pole. And in the real world you hit an invisible barrier - You can fly along it horizontally or vertically (Well, between the ground and 100,000ft - Another invisible barrier), but not through it.  :-D  :crazy:

I wonder what the map really looks like, 'cause by this im pretty sure it ain't round...