I think there’s a massive difference in the virus between the virus becoming less potent due to
a) the biology of the virus changing, and it mutating into a less dangerous form, and
b) human behaviour having squeezed the virus’s ability to transmit, especially in large infectious doses.
The article doesn’t make it clear which of the two is believed to be the reason (though it could be a bit of both), but until a lab shows the virus has mutated, I think the working assumption should be b).
Of course, even if a less virulent strain has evolved in Italy, it doesn’t mean that the more deadly strain isn’t spreading elsewhere in the world that could be reintroduced given a chance. It’s not like the virus in Italy says to its cousins in Brazil “hey guys, we’ve mutated into something else, you need to make the change too!”
As long as no one is thinking “phew, Covid’s gone away” as a result of this kind of article, that’s fine.