There are so many misconceptions in the above paragraphs its hard to know where to begin.
False. Your are living in the past. This statement hasn't been true for some time. Most people who start smoking today do so at legal age. I know we have been lead to believe that nearly everyone starts smoking under age (18) but more recent surveys are showing the demographics are changing.
tobacco control still clings to the concept that most smokers start under age because it suits their agenda, but the reality is something else. Smoking rates have stayed fairly constant since 2000 yet youth smoking is at an all time low.
part of the policy reasoning and goals of tobacco control was to reduce tobacco use in society This appears to be at the core of your argument but is very tortured logic. First off you are confusing TC (tobacco control) with the FDA and interchanging them. They are related but not at all the same. It creates a good deal of confusion as to who is who and what you are actually trying to say.
The point you are missing, and your more tortured logic about the possible dangers of vaping (even though so far there are no real long term risk we can point to, and certainly no known short term risk, so any real risk is skating on thin ice) is THR. In order to understand a very likely future, assuming no outragous restrictions from the government, we have to look to Sweden. Sweden is the place where THR has largely become public policy. Sweden has the lowest smoking rate in the EU by a long shot, and the lowest of any developed country in the world, but has about the same amount to tobacco use as the rest of the EU. People have not quit using tobacco, they simply switched to low risk snus.
We can expect the same in the US. As people become conscious that there are ways of using tobacco and nicotine that are vastly less harmful then smoking the over all use of nicotine may actually increase in the US because of the artificially induced abstinence now taking place. Of course as people switch (and new users forgo high risk smoking and begin and stay with alternatives) smoking rates fall, just is it has done in Sweden, but overall public health increases as the risk of the alternatives is so low compared to smoking. You are under the idea that increased nicotine and tobacco use is a negative but that is simply false. As far as public health goes the only thing that matters is how many people are smoking cigarettes. If smoking continues to fall its all good (with the exception of the Puritans who will never be content until we are all living lives of purity and goodness.... at least their version of goodness)