why do you think it's likely mild
I have to admit it is partly due to wishful thinking. But the other reason is my experience with how the 2009 H1N1 swine flu pandemics played out.
I vividly remember the reports from Mexico at the time with CFR estimates of 10% then 1-5%the media full with comparions to 1918 spanish flu, and the reports of healthy young patients all over the world on ventilators with severe pneumonia.
As the pandemic unfolded, two things became more and more clear: 1. it was hopeless to try to contain it and 2. somehow the proportion of very mild cases increased dramatically until in the end it was even less serious than the seasonal flu.