I'd love to see professionally filmed rehearsals. I'd prefer to go to a concert of course.
Not sure about the prospects for 2021. They won't have much data on how long immunity lasts beyond 6 months at that point. When you consider the number of people attending a whole tour and the rules and circumstances in different jurisdictions it could become very complicated.
Here is a situation where lay-people have misunderstood headlines.
There is absolutely no reason to believe immunity won't last. The immune response to the novel coronavirus, as observed thus far, acts just like other coronaviruses about which we know including the SARS-1 from 17 years ago. Patients who gained immunity from that virus either by vaccine or surviving the virus still show great immunity 17 years on.
When a scientist examines samples from people who had covid 6 months ago and finds great immunity, as a scientist all they can say is "we can report immunity after six months".
There's a lot of misunderstanding about antibodies declining too. That's perfectly normal and to be expected. THe human immune response has (at least) two stages/lines of defence. In the months after an infection or vaccine, the body creates antibodies which swim around the body in the blood cells waiting for a new encounter with the virus. After some months the concentration of antibodies reduces and the T-cells retain something one might say is akin to a "memory" within the bone marrow...the body remembers how to make more antibodies should it need to months or years even decades later.
The scientists studying this virus and our immune response cannot say for sure "immunity will last for years" because the first cases were not much more than a year ago. 16 years ago they said the same about SARS-1.
No scientist worth his or her certificates is going to actually say that, because that's not how scientists communicate their findings. But a paper is published "SARS-COVID-2 immunity lasts at least six months" and some news outlets try to spread panic, spinning that to "Covid immunity may only last 6 months, top boffins say! Panic! Disaster! Buy more bog rolls!"
BTW...the above info was paraphrased from the chap who discovered the covid antibodies and from a good friend of mine involved in medical research over 25 years.