Based on my research, it actually seems like fatality rate will NOT skyrocket if our medical system is overwhelmed like in Italy.
Here is an actual study that looks at fatality rates in Italy vs China after stratifying by age group: https://jamanetwork.com/journals/jama/fullarticle/2763667
The most eye-opening graphic is the first chart. To summarize the article:
1) Italy's fatality rate for patients younger than 60 is actually better than China
2) Italy's fatality rate for patients older than 60 is less than double that of China
3) Italy may have a higher rate of pre-existing conditions which makes fatality rate look worse than it is
4) Italy is only testing symptomatic patients which makes fatality rate look worse than it is
All of these results were surprising to me. The information being spread by the mainstream media suggests that if hospital systems get overwhelmed like they have in Italy, fatality rate will skyrocket.
In reality, it seems like we're dealing with a classic case of Simpson's paradox (https://en.wikipedia.org/wiki/Simpson%27s_paradox). If you stratify data by age group, you find that even if hospital systems are overwhelmed (to the same degree as Italy), fatality rates will, at most, double.