Well nicotine is derived from the tobacco plant, you had to know lawmakers would go there eventually if vaping got popular enough.
The FDA regulates what it decides to regulate (and what it has funding for). However, if vaping is placed on their plate, I'm sure they will have a good time doing what the FDA does. With that said the FDA is underfunded, often doesn't do a great job collecting and dealing with too much of anything these days.. That is why some of the statements coming out of it was pretty useless and misinformed.
I was told at one point that the FDA would LOVE to regulate OTC aids of many sorts (particularly herbal sorts) but they simply don't have the funding and staff to do it with.
There is no good, really agency for evaluating overall safety to vaping products . You'd need engineers for the mods, battery experts for the batteries, chemists and toxicologists for eliquid, the list goes on. The FDA will do whatever (halfway measures probably) it can come up with and based on their director's plans who was appointed by Trump. I am not holding my breath at the moment regarding the FDA.
Anna