If this were to happen, there are a few ways around it:
First of all, banning the device itself is unlikely. The device itself poses no danger to anyone, it's only the ingesting of the liquid that is a potential hazard.
Keep in mind that it is perfectly legal to buy a glass pipe, water pipe (....), or vaporizer for "tobacco use" when in all reality almost no one smokes tobacco out of a ..... You can bet your ... that if things could be banned for "potential" illegal uses, these things would already be illegal. If such a device is confiscated by police, it must be tested and found to contain traces of illegal substances before you can be charged with anything, which is why they can sell them unused. They cannot prove illegal intent in cases where it's never been used. This gets a bit murky if you would be found in possesion of other illegal substances however.
Nicotine is not illegal, and making it such would hurt big tobacco so much that I cannot see it happening.
Go to any college town in America and ask where the local headshop is located. You'll find a dazzling array of vaporizers that work just as well for e-liquid as they do for vaping "tobacco" or "other herbs. The I-Inhale is certainly not the only one on the market.
As far as the juice, it can be made at home (grow your own?
)
Anyway, my 2 cents, but I really hope we're all just paranoid with all this stuff.