I disagree. If we're in a slump then people will be poorer and good public transport will help them access the jobs that do become available. Cutting infrastructure will prolong the shutdown: The 1930s were a downward spiral until the war made governments spend, which wound the economy up again. Britons were kept exceptionally poor after the war because of the national need to pay back loans. Admittedly Germany and France restarted from a more badly damaged infrastructure, but it was the re-building (with "Allied" money) that got their economies going and made them generally more prosperous than us in the 1960s and 70s.
The thought behind the long back to normal passenger flows isn't to do with how well/badly the economy is doing. It's more to do with the fact that by flattening the curve we'll likely need to keep staff who are able to do so working from home for a long period of time.
As such chances are we see restrictions on going to school relaxed in September, but the request for those to work at home to continue to be asked for some time yet.
Whilst reopening schools would increase the risk of transmission, leading to more cases, as long as there's been a good number of cases and the reinfection rate has tailed off then the risk of overloading the NHS should be fairly small. However if you reopened offices as well then that risk could be too high.
Other workforces could return to work (such as construction and building maintenance along maybe some more relaxations on retail and leisure) to limit the harm to the economy.
The other reason for the circa 2 year period is so that it gives time for a vaccine to be develop, tested and roll out to be well advanced before allowing significant rail travel (with the potential for significant numbers of people to be infected).
Aviation is likely to be hit hard and is unlikely to recover to the levels seen before. Not least as there'll be a change mindsets about the desire to travel quite so freely. Also with any negative change to economy it would also result in people having less money to spend on luxuries, as well as a desire to have larger reserves of money incase there's another 6 months of lockdown with limited chances for earnings (or at the very least replenishing those reserves which have been depleted).
Whilst this would also have a negative impact on rail travel for leisure, this is likely to be offset by those saying "let's stay in the UK rather than going abroad". Especially if you'd be going to places where a vaccine hasn't been so widely distributed (such as those places where the citizens have to pay for it). As travel to such places could result in the increased risk of picking up a mutanted version which does infect you as the vaccine doesn't protect you from it (much the same way as the flu vaccine has to change every year).
If there's a vaccine, I'd expect that there would be requirements from countries that anyone entering from abroad (regardless of if they originated from that country, so if you or I went on holiday we'd need to have had the vaccine before we could re-enter the UK, even if we could go into, say, Spain without such protections) would need to have had the vaccine before they are allowed to travel. Quite possibly at least 2 weeks beforehand. That's likely to further restrict international holiday travel.
Chances are a roll out of the vaccine would be test and then once you've got the results get the vaccine I'd you've not been exposed. In doing so it would minimise the number of people needing to be vaccinated early on. To provide better protection to the population at large you may well vaccinate everyone at a later date with a second dose just to be sure (i.e. in case someone had a false positive result for having had the virus during the testing phase).
