I dont necessarily agree, as technology has evolved, many wrecks which were thought to be unfindable have been found.
Bismarck at 17,000 feet:
Titanic at 12,000 feet:
USS Thresher at 8,400 feet:
http://www.history.navy.mil/photos/s...t/ssn593-l.htm
USS Scorpion at 10,000 feet:
http://www.history.navy.mil/photos/s...s/ssn589-k.htm
As to what the wreck will look like will really depend on what caused the sinking. The USS Thresher imploded and debris was littered all over the sea floor. However, both the K-129 and the USS Scorpion flooded and parts of their hull were found on the seafloor.