Herd immunity as a long term strategy isn't discredited at all yet. It's the only long term strategy there is. Short term strategies it's no use whatsoever.
The government haven't helped themselves. I do wish they would publish in more detail the evidence and thoughts on how children spread/susceptible to the virus and modeling on schools. The sage advice should have been published earlier.
Enquiries could focus on testing and things like whether London should have been restricted a week and a half earlier. Whatever went on in care homes and the lack of government support there.
If a vaccine is impossible, then by that time quite a lot of information will be known about the virus having failed to find a vaccine multiple times. That information will be useful. Apocalyptic scenarios might be that a lot of more sophisticated work goes into shielding a small percentage of the population and genetic testing. Other nightmare scenarios are it takes so long to make a vaccine that significant mutation has occurred. A more likely scenario might be a vaccine offers some immunity but doesn't perform as well as wanted, this does happen for strains on flu vaccines.
