ORIGINAL: Erik Rutins
The decrease in China in that view is partially masking the exponential increase elsewhere. Cases are now appearing in most countries around the globe, including those with poor health systems. It's still spreading at a very high rate even in advanced countries implementing social distancing and contact tracing. That's what is leading many to say that this is now an inevitable pandemic, projecting forward a few more weeks. If we are very, very lucky, it will not be but there is no indication at this point that is is containable without excellent preparation and very significant proactive measures for a long period of time.
We are thinking along the same lines. The good news so far is that it is appearing to be less transmissible than the flu.
The mortality rate is getting better and better estimated as time goes on, so the current WHO estimate of 3.4% is bad news, and I seriously doubt it's an instance of scaremongering. I'm not sure (as I think Kull commented below your post) that the mortality rate is a projection based on medical care availability, it's my impression (I could be wrong) that it's historical. Given how overwhelmed the medical system became in Wuhan/Hubei that amounts to the same thing, and I agree (with subsequent comments) that any nation's medical system could quickly become overwhelmed with this.
I read an brief article of a study which found that it is possible certain gene pools are either less susceptible or not susceptible to this virus (most of the population of sub-Saharan Africa and of course anyone with the relevant genes). If so, that would provide some relief.
Let's suppose the mortality rate is only 2%. If 1,000,000,000 people get COVID-19, that's 20,000,000. If 3.4% that's 34,000,000. It's quite possible that far more than 1,000,000,000 people will become infected.
Much depends on slowing the spread of COVID-19, developing effective treatments, a vaccine...