We are confident it will go forward (first Greek in June). We have airfare, hotel, and some tours booked (from previous credits). Should we be unable to cruise, we will turn it into a land trip. But I don't think that will be necessary.
I am not concerned about testing at port. By the time we get to next June, all of us will have been exposed to COVID one hundred times over, making it unlikely that is the time we finally get it (some of us had had it in addition to being vaccinated). We can test before we depart and if we happen to be extremely unlucky to come down with it on the way over, then so bet it. The possibility seems remote. If get get stuck in Europe, I can easily work remotely too. It's a risk we are willing to take at this point.
Either way, we are excited and ready to go next June. It's our children's first trip to Europe and there was a time not-to-long ago where we thought my wife's health wouldn't allow this type of trip. I expect it will a true once-in-a-lifetime type of experience.