I think late Q3 or Q4 of 2021 will be when things start to return to normal in the US
The primary unknown about the vaccines in their current state is whether they are preventing infection entirely or significantly reducing infection severity. The secondary unknown is the duration of the protection offered by the various vaccines.
The first point is relevant because, frankly, most of us on this forum won’t be eligible for a vaccine until pretty late in the cycle. We’re relatively healthy, relatively young, and relatively likely to be ok if we get infected. If the vaccines only mitigate symptoms - that’s still terrific! However, as a non-vaccinated person you might actually become more likely to be exposed in this interim period. An increasing number of people will be vaccinated and may be walking around with asymptomatic cases. Hopefully the vaccines, or at least some of them, will fully prevent infections or prevent spread while infected and this won’t be a consideration
The second point’s relevance is fairly self explanatory, but if the duration of protection (which will surely vary based on vaccine) ends up being relatively short, then multiple doses will be required - potentially quarterly, annually, who knows.
The reason I mention all of this is that, completely aside from the frightening spike in cases we’re seeing right now, I think too many people (in my general life, not so much in this thread) see the vaccine progress as a panacea. It is worth understanding that it is only the beginning of the end. Even with a fully successful vaccine (full protection from infection, lifetime duration) we won’t have fully vaccinated (70%+) the population until sometime in 2022, although in developed countries we will likely hit that number soon enough that life returns to normal just in time for a normal holiday season in 2021.