An internet posting from a fansite person is not reason to start cheering.
Here's the reality:
LETTY LYNTON was the subject of a very famous plaigiarism case, which went to the Supreme Court, and which MGM lost.
The authors of a play called DISHONORED LADY sued MGM and won the case.
DISHONORED LADY was registered for copyright in 1930, which means that the work that was plagiarised will become public domain in the U.S. during the year 2025.
Warner Bros. owns the motion picture of LETTY LYNTON, and holds a valid copyright to that film, as the successor-in-interest to the 'old MGM'. However, they would not be able to distribute the film unless they are able to negotiate an agreement with the heirs of the two authors of the plagiarised work.
It's not impossible that WB could take the steps to clear the film, and given their efforts to free up other long-embargoed works, there is hope...
For those who are interested, the link on wikipedia that summarizes the famous Letty Lynton case is below: