Smallpox was eradicated. The likelihood of the same happening to SARS-CoV-2 is lower. At least, it would be the first example of a respiratory infection being eliminated. Influenza hasn't been eradicated and it does continue to evolve.
More broadly, the idea of "immune escape" is hardly something I can lay claim to. You can read about it in existing literature.
The difference is that the smallpox vaccine prevented infection of the vaccinated. That's not the case for existing SARS-CoV-2 vaccines. https://www.verywellhealth.com/covid-19-vaccines-and-sterili... gives an approachable overview of the difference.
Smallpox was eradicated. The likelihood of the same happening to SARS-CoV-2 is lower. At least, it would be the first example of a respiratory infection being eliminated. Influenza hasn't been eradicated and it does continue to evolve.
More broadly, the idea of "immune escape" is hardly something I can lay claim to. You can read about it in existing literature.