This is sort of a depressing subject, but I'm curious to hear other's opinions.
Tourism to Ireland seems especially sensitive to social-distancing, etc. since so much of the attraction for many is the music and the people. There are, of course, fascinating sights that would be interesting in a complete vacuum.
Although I'm currently planning a fourth trip to Ireland (and second to Scotland) for June 2021, and I won't cancel my plans until next winter (which is the earliest I can get reservations, anyway), I'm wondering what things might be like. The NY Times has a very long article in today's paper outlining the potential long term oscillation of quarantines, etc. as we try to re-open for business too quickly, lasting potentially for years, depending on vaccine or treatment availability and effectiveness.
The rosy scenario of everything returning to normal in June seems unlikely. On the other hand, if things remain just "odd", we might find bargain airfare, reduced B&B and food prices, and reduced traffic. Might be great if you were headed to the beach or to see the pyramids, but not so great for cultural immersion.
One thing for certain, I wouldn't make non-refundable reservations! Troubling times...