This thing moves too fast. Without mitigation, 1/3 would be exceptionally lucky.
There never would have been a 100% unmitigated response. People would have self isolated and the cities would be desolate. But they would have infected half the country in their panicked flight. No place would be safe. No amount of prepping would be good enough for the majority of people.
Likewise, 90% is improbable. But the infectiousness and stealth capabilities of this virus are a formidable combination.
Likewise an effective cure for the Wuhan Virus won't materially reduce the total number infected. It just means less will die or suffer permanent impairment.
The Spanish Flu was not mitigated on any significant scale, yet the total proportion of those infected worldwide and in the US varied by less than 4% - 500 million of 1400 million worldwide (35.7%), and 31 million of 103 million Americans (32%).
I'll use the 1918 Spanish Flu as a model for one-year infectiveness for a virgin field airborne-transmissible epidemic until there is convincing evidence to the contrary.
Note that I have always postulated multiple waves of infection for the Wuhan Virus over a one-year period. This is simply NOT a One-And-Done disease. It will hit us with periodic waves until it mutates to a less deadly form, humanity develops herd immunity, or an effective vaccine is used worldwide.
The media is incapable of learning this until this first wave subsides and a second one comes along. Medical authorities are too wrapped up in dealing with the Now to look ahead six months. The only thing American politicians are looking ahead to are elections in November.