I don't know whether I count in the doom-monger camp?
The vaccine roll-out is amazing BUT we need to think about it sensibly and calmly, rather than assume that 'being vaccinated' = 'being safe to act completely as normal'.
We have to think about those who are not immune, whether they have been vaccinated and this has not been effective (most likely in the elderly and immunocompromised, already vulnerable); whether they have been partially vaccinated (having had only 1 vaccination or not yet having had time for their vaccines to have full effect); or whether they are not vaccinated at all (most probably due to age).
In a 'normal' scenario, those without immunity are well separated in society, so if someone is infected, the infection does not spread rapidly from them because of the protective 'ring' of those with immunity.
In the 'Covid immunity created by vaccine' scenario, while those who have not developed good immunity after vaccination are fairly randomly distributed, the unvaccinated are all gathered together in particular places (schools and colleges, for example). This means that while percentage fully vaccinated in some groups within society is reaching enough for herd immunity, there will not be genuine herd immunity until there is the right percentage vaccinated / have gained immunity via infection in certain groups, and unfortunately these are also the groups gathered for long periods daily in the most Covid-unsafe environments such as schools.
so vaccinations WILL be effective, of that I am confident. however, to truly achieve herd immunity, either those uder 18 will have to be fully vaccinated too, in numbers enough for herd immunity, OR we must still go through the very painful process of allowing Covd to naturally infect 80-90% of children and young people - with all the possibilities for mutation and infection of others that presents.
We will be OK in the end, but we are further off the end than many people think.