It DID materialize. The bulbs you are buying at retail are the ones that are exempt.

I recommend this website: https://insights.regencysupply.com/state-light-bulb-bans for looking at lamp bans in the US.

It did happen, it was the same ban that also banned most lamps with a lumen efficiency under 45LPW.

I think the only low voltage halogen lamps affected are 12v MR11/16 and possibly also including G4 halogen lamps with a lumen output above 300.

One question : IF a complete , outright ban on halogen does occur , what about automotive headlights ??

In the USA it is against the law to install LED retrofit lamps in place of a Halogen bulbs as the housing is NOT certified for that source
I assume they are and will stay exempt for a LONG TIME