What we know...
The FDA's designation of mech/mod parts as "tobacco products" is strictly for the purpose of taxation. I suspect the tobacco industry is going to take over the liquid industry via FDA ban on the sale of nicotine base liquid to anyone who is not "licensed" to posses it. Vaping is a multi-billion dollar a year industry, and they have no intention of leaving it in the hands of "the people".
My prediction...
I don't believe we will be left with "cig-a-like" devices only. They know mods are hugely popular, so you can bet they will continue to be sold. There won't be anywhere near the selection, but mods will be made available. Mods only... Nothing non-regulated. I suspect they will choose three types, and that will be it. Cig-a-like, e-pipe, and mod.
Anyone producing and selling nicotine e-liquids without a license will be deemed "bootleggers", and prosecuted accordingly. I also suspect that corporate e-liquids will (like cigarette tobacco) formulate their liquids with additional chemicals to increase addiction. Dr. Jeffery Wigand referred to this as "boosting". Since quitting smoking, I've never felt the urge to vape, regardless of the nicotine content. This has me convinced that big tobacco does in-fact engage in boosting, as Dr. Wigand stated in his 60 Minutes interview.
As a smoker, I could barley get through a 2 hr movie without feeling the need for a smoke... Not an issue with vaping! I enjoy vaping, but I never feel like I need to do it.