I live in the US and I can guarantee you that paintball will never be banned here. Gas will always be available, becuase the gas we use is used by welders, divers, and who knows who else, so compressed air and CO2 will always be available. Unless new laws are passed, markers will never be illegal to buy or own here. You can legally own a firearm here, so I doubt that markers will ever be banned (if anything they'd be restricted, and even that is unlikely). The destinction between markers and guns is pretty much established here (markers aren't classified as firearms, because in the technical sense, they can't be. A firearm must use a controlled explosion to propel projectiles, and markers do not, they use compressed gas), so they couldn't ban markers on the basis that they are guns (that would be oxymoronical anyway, since guns arent' banned).
If paintball is banned, then the 'ballers in this country will pipe up, let their opinion be known, and take it to the streets and to the courts. Over 6 million people here call themselves "paintballers", so that's a poweful voice if we all band together. If paintball is banned, I will strongly oppose it publicly, and they will have to kill me to shut me up, and I'm sure most 'ballers feel the same way.
I think you are wrong, I don't think paintball will ever be banned, perhaps restriced, but never banned. At the most, markers may require a license (don't freak out, fishing requires a license too), and I wouldn't be surprised if they passed a law that markers can only be discharged at licensed, insured fields (which I'm not against anyway, put a fine and jail time on anyone who discharges a marker in public, or on non-specified land, and they will stop. Plus it will put a better light on our sport)