There are numerous reasons why we are incapable of a perfect lockdown of a region of any reasonable scale even before economic concerns. So it's use as a solution is more of a whataboutism for not considering reasonable actions.

How will you address the animal reserves? This virus is not eradicable.

Do we know it can actually stay in animals long term in a form compatible with humans?

I don't think this is true. The virus can survive in some for a long time. Same as with the flu. I think the endemic phase is absolutely inevitable. The only question is how long does it take, and how many people will be killed in the process. Both can only be reduced with vaxxination.