That's what I reckon though. It's not unprecedented - DS and PSP titles have done this in the past. And if the system is smart enough, it can stream content on demand quite efficiently, keeping waiting time low, especially if someone has a half-decent connection. It certainly caught my attention as well though - the question is if it amounts to more than a demo or not.
Surely if the friend can afford a decent enough connection (my fiber optic is not exactly cheap and I'd dread to do such a thing on anything less) and a desire to play FC4, he can afford it - even discounted or second hand?
I also think this whole multiplayer-without-game will be for very short demo-like sessions.
Then again if it's anything like FC3, I don't see how anyone would not want to run to the shops and pick up a copy after playing 5 min of it. Maybe that's the point.