Whether or not a vaccine could work may depend on the current scenario.
Current timeline dictates that different cities peak at different times. While COVID-19 might not really go away, it can be possible that the outbreaks will be more localized and turn into endemics in the future. Hence, the priority should be made to avoid reinfections.
Before a vaccine becomes reality, the world over must adopt measures which work towards preventing reinfections. Identifying the ones exposed, contact tracing, maintaining safe distancing and enforcing strict quarantines for those who have been exposed, along with repeated serosurveys could help confine the spread of the infection. Scientists have said that countries with the lowest coronavirus rates practised this and successful quarantine measures have been helpful in limiting COVID spread to near zero in some places.