So it's just a small radio? Lol, how the fuck are they going to manage this? Even if they went full North Korea you can make a little SDR from e-waste.
There's a chance they'll take the approach they did with guns and just pick an arbitrary collection of specific products. And if they do, it'll be just as much of a a "dog and pony show". You'll still be able to buy and use radios, including ones that can tune to whatever frequency (probably 13.56Mhz).
It's a bunch of antennas. Low GHZ radio, RFID, NFC, Bluetooth. It will also read/write those button-cell keys. There's also GPIO for you to create your own add-on hardware.
I have no clue how they plan on outlawing them, but it's going to be some reactionary knee-jerk law that does more harm than good.
If the concern is car theft, go after the vehicle manufacturers that aren't using rolling codes and properly securing their vehicles.
Other than the one wire connector and the IR, most phones have all the same hardware and much more compute power, there is nothing stopping a rooted phone from doing the same thing. The Flipper is just an easy UI on a cool form factor.
It sounds like a lot of the thefts work based on the principle of amplifying the fob so it seems close to the car even when it's not. Because all reasonable EM radiation can be amplified, there's no simple way to beat that short of going back to requiring a fob button push, so it's basically convenience vs. security.
They could try fobs that are smart enough to guess whether they're being handled normally when activated, but that will 100% annoy consumers any time they try and do something the software doesn't expect. It could even get as bad as the consumer putting the fob on a flat surface in another vehicle, and gently driving it up to the vehicle they want to move into.