Right now it only shows a little bubble in the URL bar saying "Not Secure", I think. (So, that is a "warning", in a sense.) TFA is saying there will now be an interstitial if you attempt an HTTP connection.

HSTS might also interact with this, but I'd expect an HSTS site to just cause Chrome to go for HTTPS (and then that connection would either succeed or fail).

> to force network-level auth flows (which don't always fire correctly when hitting HTTPS)

The whole point of HTTPS is basically that these shouldn't work, essentially. Vendors need to stop implementing weird network-level auths by MitM'ing the connection, and DHCP has an option to signal to someone joining a network that they need to go to a URL to do authentication. These MitM-ers are a scourge, and often cause a litany of poor behavior in applications…