CoViD-19, allegedly, has a death rate of 2%, although it's most likely a lot higher than that, but let's just use that number. From the numbers in the OP, they anticipate a flu death rate of .00055. CoViD's, by comparison, is .02. That makes CoViD about 40 times more deadly. If CoVid becomes endemic, as you mention and as we have seen very credibly predicted, and only spreads as fast as the flu (and most estimates put its R0 considerably higher than flu), that would mean 580,000 people will die from it every year given an annual infection rate of 29 million. Those most likely lowball numbers would make it the third leading cause of death in the US, just below heart disease and a very close third to cancer. If you tweak the death rate a bit and set it at just 3%, it blows past both of them to become the leading cause of death.