According to what I've read, Italy has done more testing per capita than the U.S., not less. Which suggests that its high death rate is real, and likely caused by the age of its population and especially it's lack of equipment.
No, we don't know how bad it will get in Italy. But we do know that Italy has flattened its curve on new cases added, going on over a week now.
Italy Coronavirus update with statistics and graphs: total and new cases, deaths per day, mortality and recovery rates, current active cases, recoveries, trends and timeline.
www.worldometers.info
Which suggests that it will remain roughly where it is, for now, then at some point the cases and deaths will start to decline. And as you said, they have an aged population and higher population density by far than the U.S. They were also ill-equipped from the get go, not "we're going to run out of ventilators by the end of next week" but they were out of everything in days.
It's hard to predict how something like this will turn out. I'm just making an educated guess based on existing data. But I'm sticking to the 100-200K estimate for now.