Have any countries with estimated cumulative infection rates similar to the U.S. experienced second waves where fatality totals approached earlier peaks?
Going by information at the Worldometer site, for example, Spain, France, and the UK have experienced cumulative reported per capita COVID deaths ranging from about 25% lower than the U.S. level (in France) to about 6% higher. I take that as evidence that the cumulative level of COVID infections in each of those countries is broadly similar to the U.S. In each of those 3 countries, the 7-day average of reported daily COVID deaths during a recent second wave has—at least so far—stayed below 20% of peak levels in the spring.
So you are arguing about the size of a second wave in the US, not the likelihood?