You are correct - after the Brigadier Tactical was introduced, Bill Wilson previously stated on Beretta forum that he has two other projects planned with Beretta USA. He stated one will be smaller than a Brigadier Tactical and larger than a compact. I agree that the Centurion size is a logical progression. He also hinted that the other will be neither a 'FS' or 'G' (D or SAO?)...but GJM noted that Bill Wilson builds pistols he likes to shoot, and Mr. Wilson doesn't carry a D or SAO model...however he has sometimes paired the 'D' upper with 'FS' lower...
Just because I like stirring the pot with rampant speculation and old posts...