At 23°53'S 103°58'E the water depth is 18,160 feet (5,535 meters) and well beyond the ability of the Blue Fin 21 UAV. This job could well need the Remus UAVs used during the AF447 search.
I'm thinking the main thing for it to do would be a good side scan sonar mapping, what depth can it do for that.
Yes a good visual at optical would be good. But I think that at the depths where talking about, a solid confirmation on anything and its position would be a godsend.
Then good practical planning with the right equipment can be done on what can be recovered.