Would Hood make older American battleships obsolete?
Short answerNo. A battlecruiser can avoid a battleship, but it does not have the protection to make battleships obsolete in a direct fight.
NotesChoosing an engagement is different from surviving in the battle line. A battlecruiser can use speed and manoeuvre to avoid a slower battleship, but that freedom does not erase the battleship's protection or firepower. If the battlecruiser accepts a direct fight, each hit is likely to hurt it more because it lacks equivalent armour. It therefore needs repeated success in positioning and damage avoidance, whereas the battleship can absorb mistakes more readily.