Obvious shift?

North’s jump to four spades showed a spade fit with a terrible hand, usually 0-3 points. North would have bid only three spades if he thought he had anything useful. West started with the ace and king of diamonds, then continued with the queen of diamonds. South ruffed with the 10 of spades and cashed the ace and king of spades to draw trumps. He cashed the ace and king of hearts before leading the eight of spades to dummy’s nine. In dummy for the only time, South had to decide what to do. He made the winning decision when he led the 10 of diamonds. He was delighted to see East discard a heart. South discarded his low club, conceding the trick to West. West was not at all happy about this as he had to either lead a club away from his king or give up a ruff-sluff. 10 tricks either way and South made his contract.

West could have done better. Surely his partner would have highlowed in diamonds on the first two tricks if he had a doubleton. There was no chance that the queen of diamonds would win the third trick. He could have shifted to a trump at trick three. Declarer can still arrange for the nine of spades to be a dummy entry, but he will have no better choice than to take the club finesse for his contract and the defense would have prevailed. Was this an obvious shift? What do you think?