What if there is never a vaccine for this? There have been no proven vaccines for any coronavirus and only limited evidence that the immuno response lasts for up to 18-24 months.
There may be some promising developments currently but there is no guarantee that we'll find a solution to this.
In most countries around the world, less than 0.5% of their populations have been infected. People have wrongly conflated flattening the curve with getting rid of the virus or limiting the deaths, neither have been the goal. It has always been limiting the impact on healthcare services and not overloading them to ensure that every person can get care in illness, covid related or not. If you overload your systems, that's when you get mass deaths.
It takes a single person to create a new outbreak. Without proven herd immunity and a yearly vaccine ensuring maintenance of that, learning to live with it is a very real reality. Forcing use of PPE, regular testing, contact tracing and social distancing measures are essential. No one can survive multiple year lockdowns, so finding the correct balance is essential, unfortunately many governments will absolutely get it wrong.