PilotLZ
If you actually run the numbers on that strategy it doesn't look so good though.
Using UK figures (self-interest herby declared) the vulnerable number around 10million, (8.7 over 70 + >2 clinically extremely vulnerable, self-interest herby declared on the latter), there will be some overlap so call it 10 (the priority groups being vaccinated also include few million health and care workers etc.). NHS reckons 10% infection fatality rate for this group, which seems about right (most of the deaths so far with lower infection rate than the 20% population overall due to shielding etc.). Lets assume we don't care about anyone else or about long term damage to survivors (possibly more prevalent in younger groups).
Assume if we let it rip through everyone else we end up with around 80% exposed - Bergamo reached 70% 1st wave before a lockdown, Manaus got to over 60% but then had a second wave on top of that.
Also assume a "back to normal" means the vulnerable will see the same attack rate as population as a whole. Note: Newer variants, including the UK one, might well go higher.
Assume (optimistically) no new variants with vaccine-escape mutations (remember the bigger pool of virus/hosts the more likely mutations are).
Assume (optimistically again) no reinfections, or that reinfections are lighter and add no further mortality risk (already known to be false but we don't know in how many people).
Assume (optimistically) we can vaccinate 100% of the vulnerable 10m, none of them has health problems that prevent it, none of them has weird conspiracy beliefs about Bill G or religious beliefs that it makes you gay or whatever.
Assume vaccine efficacy is 90% (ball park for Pfizer, optimistic for Oxford/AZ), thus reducing IFR for the vulnerable group down to 1%.
Expected deaths: 10m * 0.8 * (1 - 0.9) * 0.1 = 80k further deaths. If vaccine efficacy is actually 75% (roughly Oxford stated) then it is 200k.
Bearing in mind that the NHS has struggled at various points to cope (and with a lot of collateral damage still to come from cancelled non-covid treatment) with around 110k deaths over a year, looks to me like you would still need other spread-control measures (i.e. lockdowns) to flatten the curve and avoid overrunning health care (if you overrun those death rates go up further). And if the optimistic assumptions don't hold....
OR we can view the vaccines, and vaccination of as many people as possible, as one more tool to control the spread of the disease alongside the tools we have (like lockdown). We can either use the tools to "flatten the curve" (haven't done a good job at that in UK so far, but maybe vaccines will make it more controllable), OR we can use them to keep cases going down, targeting zero. Now, targeting zero sounds good to me, a declining epidemic means a declining death rate for a start, but a declining case rate means declining pressure on the health service which means people might be able to get treatment for non-covid conditions again (final declaration of self-interest...).
I think best hope for travel and aviation industry is if enough countries / areas in the world get to low-and-declining or near-zero to establish air corridors around a significant portion of the world. The holiday/leisure market will return, maybe even with a big demand bounce, holidays mostly just haven't been happening, holiday money hasn't been spent. Business travel I'm not so sure - business (in other sectors at least ) has carried on and been forced to find other ways to work, some of that change may well be permanent.