Does this affect foreigners? If I have a AT&T plan, it should work out-of-box in China via roaming? Hope that is the case...
The plan could affect foreigners but it was hard for years already, in that most cellular stores require a Chinese ID to register monthly service (not all take passports). I used to get the salesperson or security guard to lend their ID in my stead, and this is exactly what this policy seems designed to prevent. Hotels and train stations have operated under facial authentication for a couple of years too for Chinese nationals. This seems to be along the same vein, to ensure the person is who the ID says they are. In other words, it's handing over the ID-checking from a person to an awkward police-sanctioned box.
I’ve only successfully roamed with T-mobile on WiFi. Maybe its better now?
I roamed on T-Mobile pretty successfully using a cell connection last year, but I had to buy a $20 1G data pass and some other passes for it to work. It was worth it for the reliable unfiltered internet access.
My current T-Mobile One plan was worse for this than my old grandfathered (Select Choice?) plan, which could limp along at 2G speeds out of the box and only needed the data pass for usable speed.