Could they? Sure. The gov't can, and will, do anything they want. However, even if they do all is not lost for a couple of reasons.
1. Nicotene inhalers. They're marketed as nicotene replacement therapy, but they're kinda like vaping. I suspect eliquid could be made from those.
2. The existence of nicotene inhalers makes me think they're not too worried about it.
3. Blu was bought by a Big Tobacco company (Lorillard). To date, they haven't done anything new with the company, it seems as though it's rolling along just like it always was. Seems like more companies would be interested in picking up e-cig companies as a way of holding onto potential customers. If a person quits smoking and starts vaping, and you own an e-cig company, you may end up retaining them as a customer. If a person quits smoking and e-cigarettes are illegal, there's no chance you'll retain them.