When before the last postponement I thought this would apply to us, I had the following conversation with our TA.
I asked about it, and he said no worries this would be like Australia, and it would be taken care of by the airline before flying. I then pointed out we were flying into the UK, not a Schengen country before the cruise went to some in that zone. He then said he would have to research it. And soon afte, they postponed again making it moot.