There are far more influenza deaths over the last 3 decades than ebola, but ebola is far more severe and greater concern.
I think that's probably wrong? The most likely outcome would be that after the initial pandemic subsided (with lots of deaths), most people would catch it when they were reasonably young and then be mostly protected.
This is different from malaria, which is much more deadly.
We have a number of Coronaviruses endemic to humans that cause the common cold (among other viruses.) That's probably how covid19 would turn out, left to its own devices.
(Both are RNA viruses. https://en.wikipedia.org/wiki/Orthornavirae)
Part of what's so exciting about the vaccines is that the antibodies seem to decay at a slower rate, meaning that it could result in longer immunity (though we obviously don't know for sure yet).
If that were the case we would see large amounts of re-infection, since the pandemic started over a year ago
Then why hasn't that happened with malaria?
Getting malaria doesn't inherently make you less likely to get it again (if anything, it's the other way around)
https://www.nature.com/articles/502S2a