One other observation, for what it's worth. According to the John Hopkins site, between 29th Jan and 30th Jan updates (that's the data I happen to have access to), we have worldwide:

* 29th: deaths 133, recovered 126

* 30th: deaths 171, recovered 143

But for Hubei, we get:

* 29th: deaths 125, recovered 88

* 30th: deaths 162, recovered 90

Which looks like the death rate is going up in Hubei.

Subtracting Hubei though, for the rest of the world (but mostly China) we get:

* 29th: deaths 8, recovered 38

* 30th: deaths 9, recovered 53

* difference: deaths 1, recovered 15

Of course these numbers are too small to have real significance, but they're worth watching over the next day or two. It looks like outcomes are very different outside of Hubei from in Hubei.

It's consistent with natural selection. Cases inside Hubei likely have fewer viral generations (= less mutation) than cases outside. Additionally, every case outside has a population bottleneck in that it was transmitted through a host that was well enough to travel. The most virulent cases would be expected to sicken their hosts and discourage travel or extensive social contact.

Surely all current cases have experienced roughly the same number of viral generations? A death outside Hubei today will be caused by a virus with roughly the same number of generations as a death inside Hubei. Yet a smaller fraction seems to be dying outside Hubei.

Other possible explanations are that the healthcare system in Hubei is overwhelmed, so more patients die, or alternatively they're just too busy to accurately report recoveries.

Hubei is estimated as being max at the 5th generation, and genomes so far have indicated less than 0.02% genetic variance. I don't see evolution playing a succincts) significant role in this timescale.

Not really surprising considering medical resources in Hubei are heavily strained, not all severe cases can be diagnosed timely and given enough attention afterwards, which is not true elsewhere.

Edit: Oh you mentioned this yourself in another comment.

Just to update with the latest statistics, since 29th Jan, up to 30th Jan 9:30pm EST, for rest of world outside Hubei, there have now been 1 death and 33 recovered. So the trend seems to be that the death rate (calculated as deaths/recovered) outside Hubei is falling. Still early days and small numbers though.