What could Japan construct if it did not build the Yamato class?
Short answerCarriers and cruisers, plus some conventional battleships. Japan also had politically underused yard capacity, although using all of it would still have left infrastructure shortages.
NotesCarriers, cruisers, and some conventional battleships were alternatives to the Yamato class. Political choices left some Japanese yards and construction infrastructure unused in the 1930s, including after Japan left the naval treaties. Port visits prompted a comparison between the infrastructure available and the capacity actually employed. Even using all of it would still have left Japan short of sufficient infrastructure.