Would a three-turret Deutschland count as a small battlecruiser?
Short answerNo. It would be closer to an Alaska-style large cruiser or a new super-cruiser category.
NotesThe distinction rests on mission and relative scale rather than gun caliber alone. A nine-gun Deutschland would remain a cruiser intended to raid trade and force expensive responses. Its existence could nevertheless push the Second London Naval Treaty toward a new tonnage and gun category for super cruisers. Britain and France might then build their own 12-inch counter-designs before the war. One successful outlier can change both treaty definitions and the ships other navies consider necessary.