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Under the conservative assumptions that just 60% of the population catches it and just 1% of those infected die
Those aren't conservative assumptions, imo. They are pretty average assumptions. Of course, we don't know the first at all yet, and have no very good data on the second (since we have no idea how many untreated/asymptomatic cases there are, but very few epidemiologists have guestimated higher than 60% spread, with 40%-60% being the most common. This is based on previous diseases, so it's pretty much a ballpark, but at least they have models for it.
As for death rate, there are still a few out there estimating higher than 1%, but it's becoming a mainstream number among medical professionals (source, fivethirtyeight's weekly survey of epidemiologists and discussions with my sister who is a micro-biologist). Of course, it's still largely a guess. We can't even bound it by number of known cases/fatalities, because many of the currently known cases are still in danger, but those observed numbers are close to a max bound. On the minimum bound, we have literally no data, as we just have zero idea how many people have/had untested cases.