Intact or not?
Today when we think about a major airliners hulls reaction to hard impact with water surface, the scene where the 747 finally splashes into the waves looks pretty unrealistic, but of course it was done with that days effects.
But in real life, if a 747 comes down like that, the whole plane would most likely break apart, into major pieces of fuselage at least.
To prove this I saw a real video footage clip from 1996 when a 767 was hijacked. A tourist got the clip on film, when the 767 ditches nearby a beach. A moment later sliding on the water, the plane broke apart.