As far as in the Tomb itself, that is highly doubtful, as the soldiers inside are to represent All Unknowns. There are Grave of the Unknown Soldier, which would present a higher possibility.
Probably not. The Viet Nam vet tomb is still there, but empty, as tribute to the fallen of Viet Nam. It would be weird to put another body in the same tomb. And it'd be weird to have two Viet Nam vet tombs.
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