It could be over in 2021, but that would require widespread acceptance of a largely effective vaccine. I only have history to look toward with respect to vaccines, and our track record doesn't support the likelihood of creating an effective vaccine in such a short timeframe.

If I had to guess, most of the vaccines will fail and we will settle on the one that works the best, which wont be good enough to eradicate this virus.

Then the next question becomes, how long do our antibodies last (whether natural or artificial)? The eradication of a virus is really a fairly simple equation of % of the population that has immunity, the length of time that immunity lasts & the rate of spread.

I hope I am wrong, but the most likely outcome is that a mediocre vaccine will be used until a better one can be created and we will learn, as a society and with the aid of therapeutics, to live with this virus much in the same way we live with the flu virus.