We are on the same itinerary earlier in June 2021, and also have a cruise booked earlier in March (this is rare for us, but we already had March booked when we moved this year's Italy/Greece cruise to next year).
I am feeling like March is more questionable (given is still falls in respiratory illness season), but I am pretty confident about the June sailing.
Nobody has any idea how this will play out over the next year. We could get really lucky and it could go the way of SARS 1 (unlikely, given how this virus has spread compared to that virus), or one of the fast-tracked vaccines could be available (more likely, but still questionable). I have zero doubt that treatment protocols will be greatly improved (it appears we are already making progress here), reducing the risk of death, and it is possible a break-through treatment will work, which would be even better. If none of those happen, I think we will see this become more like how we respond to the flu. It may hit earlier in the year then it did this year and fizzle by June (based on a few articles I have read). And, we will start to put the risk in perspective better, just like we do with the other risks. People will realize that the risk of death to those under 65, without certain serious health conditions, is slightly worse, the same, or better than the flu. There is zero doubt the risk to children is less than the flu already. And the risk of death should decrease even more as some level of immunity begins to take hold in communities (which is likely based on one recent study I read). Eventually the Media (and certain experts enjoying the new spotlight) will stop feeding the fear frenzy and move to the "how do we live with it" phase.
With that knowledge, the world will have no choice but to protect the vulnerable and move on the best we can. Those who are healthy and want to take a slight risk, as they do with so many other things in life, will do so. Even the non-healthy may choose to live life to the fullest and take the risk (as many do with other respiratory illnesses each year). This will become part of life, and I don't expect the extreme safety measures to last for years on end. People and companies will become complacent and things will return to closer to the norm (hopefully without people licking sauce off their fingers at the buffets!).
I remain optimistic that what we are living in now is not the new norm, despite the media headlines. In fact, in my local community, you would no longer know a pandemic is happening. Whether that results in a spike or not, I don't see people going back to complete isolation.
Slowly getting back to normal matches the original opinion of the experts, who said we would never reduce the number of people who eventually get it, only that we would avoid overwhelming the hospitals, which we have done (maybe to a fault).
Please know that I am not attempting to minimize the loss of so many lives in such a short period. Instead, I hope for the very best case scenarios and know that, in any case, humanity will have no choice but to carry on soon.