I'll drop the thread w/ Pongo, because I feel like I'm banging my head against a wall.
In regards to betting the company on the 747, that has to be one of the scariest and best decisions Boeing ever made. There was no turning back, they developed their entire Paine Field complex around the promise of Jumbo Jet construction, and it's astonishing how good that plane is.
Last I heard, the 747 remains the fastest subsonic (and now, w/o the Tupolev or the Concorde, the fastest period) airliner in service. Not only that, but it's so versatile, it's been used or will be used as:
1. Passenger liner
2. Cargo freighter
3. Spaceship transporter
4. ICBM interceptor (w/ laser)
5. Water dropper for fighting forest fires (for some reason)
and more.