Are you by chance telling us that the actual, literal, physical "Throne of David" survived the diaspora, and will be literally sat upon by Jesus Christ when Christ returns?
Whether the old one survived or not is irrelevant, because a new one can be reconstructed if necessary. What is important is the right of the one who sits on it to sit on it. Peter says in Acts 15:16-17 that the tabernacle of David which is fallen down will be rebuilt by the one whose right it is to sit on it. What do prophets teach on the matter? Should we allegorize them away?