I'd like to suggest that focusing on flavors or combustible versus non-combustible is a mistake.
That's not how the statute is written. The FDA only has limited authority to make general pronouncements about all the products that fit a given description, although it has to regulate cigarettes differently from others, and can set up different rules for different delivery systems (gels versus cigars for example, or even premium cigars versus litle cigars).
Also, the FDA can't even consider approved therapies in some kind of public health balancing act. (In other words: if approved medical therapies such as Chantix or the patch killed every user, that would not have any bearing on how the FDA treats products under the tobacco act - the FSPTCA.)
Within products that fit a given class, the FDA can only approve or reject individual applications. And each application has to be individually supported by public health evidence for that particular product, whether that product is a 10 ml. bottle of 30% PG and 70% VG 2% nic. unflavored juice that's manufactured in a particular way, or a trippy tip that has this specific size, shape and color pattern.
Every particular juice (down to size/flavor/composition/etc. combinations) and every piece of hardware (down to the color, size, and composition of separately sold drip tips) will be treated as a separate new type of tobacco cigarette under the deeming regulations, and will be judged on its own merits with regards to its effect on public health.
So, for exampe, it's theretically possible that the FDA might conclude that one drip tip which happens to be black is okay based on the public health studies for that drip tip, but an identical drip tip made by the same manufacturer is not approved because it's made in a color which might attract children, based on the health data.
(That's an absurd hypothetical, because no one is going to do health effect studies on different colors of drip tips. But that's exactly what the statute requires for two types of tobacco cigarettes. Marlboro lights 100s are not the same as Marlboro liights kings. And the FDA has no power to make broad statements about 100s versus king-sized.)
And this is all provided, of course, that the applications are submitted - and have the required public health data.
If the applications aren't submitted, then the products will be illegal after the 2-year window closes. In fact, if they aren't registered within approx six months after the proposed rule becomes final, they'll also have to be pulled from the market.
So let's not be seduced by the general language in which these topics were discussed at this hearing. The FDA must operate according to the tobacco act (FSPTCA).