This model does not factor in the very real possibility of treatments being developed.
If we flatten the curve - and delay infections - many more will get it when the disease may well have a treatment.
The mortality will be drastically different.
(Also - flattening the curve prevents hospitals from becoming overwhelmed, which allows more people to get the best treatment, and fewer will die - PLUS fewer will die from indirect causes [deaths that would have been preventable had not the hospitals been overwhelmed - mortality above expectation]).