Could the Swordfish remain useful once modern fighters made daylight attacks too dangerous?
Short answerYes for night strikes, until widespread radar in 1943-44 made even slow nighttime approaches much easier to detect.
NotesThe Swordfish's easy days as a daylight attacker were ending by 1942. Darkness still protected a slow aircraft because visual detection and interception were much harder. That advantage eroded around 1943-44 as radar became sufficiently capable and widely deployed to find slow-moving targets. The useful life of the aircraft therefore depended on the opponent's detection network and the timing of the mission, not speed alone.