I hear you, but disagree on the basis of what you're considering "successful" to be. Successful in fully eradicating COVID-19? You're right - very, very unlikely, if not impossible. Successful in granting at least temporary protection against infection? Very plausible, with some vaccines already making it to the final stages of testing with these very same effects.
However, I'm more focused on treatments, versus vaccines. Remdesivir aside, there are many treatments on the table that are also in final stages of testing that are making a significant impact on the severity of infection and mortality rates.
I honestly think things will look very, very different come January (I mean, let's take a look at how things were in March versus now!) - and I mean that in a very positive way.
But in the meantime, keep the parks closed.