...said the flight data and voice recorders may never be found.
I'm not a commercial salvage operator, but I do dive and read up on deep/technical diving and commercial salvage operations.
According to Reuters, the wreckage lies bewteen 1500 and 2700 metres under the sea: that is incredibly deep for any salvage operation. It is far too deep for divers (the current record is 330m) and while remote operated vehicles or small submarines can reach these depths it is uncharted territory for salvage.
To get two small items from a broken wreckage at that depth will be difficult and expensive. That's not to say it can't be done, but it will be unprecedented, except for the Titanic (in 3900m) which took considerable planning.