The only way that it will be confirmed is when bodies are recovered, but there is no realistic chance of anyone being left alive on the ship and very little chance of anyone being unaccounted for.
Given the apparent sloppy ways in which passenger manifests have been compiled (according to media!!!) it's going to take a bit of detective work to establish how many people really were on board. Bodies could be out at sea and never be recovered.
When the Herald capsized in 1987, the resultant change was two-fold: Firstly, a rebranding exercise to P&O Ferries, which it effectively was at the time anyway. Secondly, and most importantly, there was a total change in the way the company operated- the positive reporting system so lacking with TT was implemented, training improved and to its credit PO Ferries today has reaped the "reward" of the changes it put in place.
Though I would lay my overdraft on the idea that there will be a new name at costa- with the same management, same procedures and same lack of care and attention.
(though if Clanky is right there might be some shiny new filing cabinets(