There have already been films with some of these titles, but most were disappointments due to bad scripts (I don't just mean dialog) and ignorance of the actual subject by the film makers generally.
Notably, "Anzio," which was a major flop, and most infamously, "Battle of the Bulge."
There is at least one British film that is quite good, "Dunkirk," made in the 1950's, though the new one will likely be grittier (and the first is not pretty).
The 442 RCT, the famed "Nisei" Regiment was also represented in the 1950's in the film "Go For Broke!" (the unit's motto). Starring many Japanese-American actors (Hollywood pioneers all), it was written by Robert Pirosh who would go on to produce the TV series "Combat," and write the classic film "Hell Is For Heroes." The film was limited by very little authentic German weaponry and materiel, but is full of action and well acted. Definitely worth viewing!
And DEFINITELY worth a remake!
There are actually any number of films dealing with the "French Resistance," fictional/fictionalized/etc, so I don't think this can be described as an ignored or overlooked subject for Hollywood.
"13 Rue Madeleine" is a terrific--and true!--story about the OSS and operations in France, and made just a year or so after the war. A remarkable performance by star James Cagney, and NOT a happy ending for anybody!
And who has not seen and loved "The Train" from the mid-60's with Burt Lancaster and a superb cast of French and German actors, as well as Paul Schofield as the Art loving Nazi.
All of which is to say that this first list of subjects is certainly not a field of virgin topics with filmic opportunities, but there are several untouched subjects that could be commercial yet outstanding.
Of course, while it may appear on a following list, it is the Battle off Samar that is the most amazingly overlooked subject for a film. It would make any American proud of what his countrymen are capable of in an impossible situation--namely, turning "inevitable" defeat and death into a victory that still beggars the imagination of historians on both sides of the Pacific.
With the effects now possible to film makers, this could be the most suspenseful, drive-the-audience-nuts film since "Saving Private Ryan"--only it would all be true.
It being politically incorrect in Hollywood to credit mostly white Americans (WWII US sailors) with any admirable qualities or services to this country (and by extension, the world), such a film is a non-starter on its face.
But a guy can hope, can't he?
TVAG