Perhaps nobody overtly wants to ban all guns in the sense of making all guns illegal. There's always a 'reasonable' proposal. But it overall feels like a roll back strategy, like the US tried to roll back communism in the cold war- pick at the edges until there's none left.

A buyback program IS a ban by the way- it's just confiscation with compensation. 'You can't own XYZ anymore so we will confiscate it from you, but we'll give you some money.

The real issue though is that guns aren't hard to make and therefore the black market effect will be minimal. Look at illicit marijuana (pre-legalization) as an example. Lots of it was grown in Mexico then smuggled in. Then hydroponic/airponic tech got better and cheaper and instead it was grown in attics and basements closer to where it would be sold. So now the drugs smuggled in are drugs that require lab processing like cocaine or heroin. But if (hypothetically saying there was no legalization) you made home-grow setups illegal, that wouldn't stop anyone from doing it anyway.

Same is true with guns. For under $500 you can buy a device that turns a half-machined block of metal into the main part of an AR15 rifle. For $5k-$10k you can buy a CNC machine that will turn a solid billet of metal into most parts of a gun. And unlike a drug lab, unlike even a basement marijuana grow op, all these devices can be presented as 'legitimate use' with very little prep- just clear the gun CNC file out of the machine and that's it. Way easier than marijuana (which takes weeks to mature and then must be harvested and packaged). So you could do this in a legitimate front business with a 'night shift' crew.

So I argue even if you greatly restrict civilian firearm ownership, the real criminals who commit the majority of gun homicides and gun crimes will have unimpeded access to guns. The same gangs that right now trade in stolen or straw purchased guns, will instead trade in imported or home-machined guns.