It looks like a good change for the average user, a secret stored on the device is likely a whole lot safer than just having a password. Having it as the only factor seems less secure than password + good extra factor like TOTP on device though.

I also wonder how a lost/broken/replaced device is dealth with, especially given Google's less-than-stellar account lockout history.

edit: I guess this is still MFA since you need both the physical device and a fingerprint and phone unlock code