Nicotine is not illegal, and making it such would hurt big tobacco so much that I cannot see it happening.
Tobacco is not illegal. Nicotine in a liquid form is not something you can lay your hands on except for our, as of yet, untested and unregulated e-liquid. Read up a bit on the subject. Google nicotine water. Look at the FDA regulation of nicotine replacement therapies like the patch and gum. None of that has anything to do with the tobacco industry. They are exempt. These other products are not. And our e-liquid won't escape scrutiny as soon as they have time to fool with it or as soon as somebody's kid swallows a gulp of e-liquid and gets hurt.