Bottom line. They will save a bundle without having to test so many guests, put them up in hotels with comped meals and the staff it takes to continue these efforts.
These July trial non-test cruises of HAL & P & O, are for 7 nights. Most likely some may be infected at the beginning and the end, but a lot will go home with it. They don’t care about it once you leave the ship.
What about the crew? Will the quarantine area be mostly for them? What about the staff shortage, if the crew is ill?
A lot to consider before jumping into the next phase.
IMO, I think the next phase may be to drop testing for the short cruises up to
10 days and continue for a bit on the longer cruises, especially oceanic ones, where there are no hospitals in case of an emergency. JMO