"Vape" has already caught on around here. You don't hear too many people say "e-cig." The most vape-naive people around here simply refer to them as "electronics" or "an electronic." Sometimes, it's used as an adjective rather than a noun, as in "Oh, that's one of those electronic things." A sign of things to come, perhaps?
I think it's partially because it rolls off of the tongue better. "E-cig" has kind of an awkward cadence. It's difficult to say without sounding like a fucking twat... ...and that's got nothing to do with connotation. "Electronic cigarette," OTOH, makes you sound like a cop or a politician. "Vape" is more versatile and intuitively easier to implement, as it can be used as a noun, verb, adverb, or adjective. It's almost as good as the word "fuck!"
Most people are naturally inclined to pick up words that can be used in many ways and lend themselves to shorter, simpler sentences, while the very concise, context-specific words tend to be avoided unless absolutely necessary (such as when it's the only fitting descriptor.) And with that in mind, what do you call someone who "smokes" "e-cigs?" An "e-cig-user/smoker?" That's kind of awkward on the tongue, isn't it? "Vaper" is a lot easier to reach for if you have it in your head.
It also helps that vape shops generally call themselves, well... ...just that. You don't see "e-cig" stores around here. People generally know that people buy their "vapes" at "vape shops" and not "e-cig stores" because the latter is not a thing that actually exists where they live.
I think that a lot of the public perception of us comes down to how we present ourselves out in the world. People will usually adopt the lingo they hear from the people they meet more readily than the lingo they read/hear in the news. Everyone knows that's not how people talk.
The news may be capable of rapidly spreading ideas and ways of describing things, but more practical and convenient terms ultimately prevail. People will usually adopt terms that are best for talking about something over ones that we acquire by reading about something. Talking to people gets your gears turning in different ways from when you're just watching/reading the news.
We unwittingly mimic the common mannerisms and gestures of those around us as a means of sort of plugging into our interactions with one another. People tend to talk in the way that the people around them talk. It's like "soda" versus "pop." If you say one or the other in the wrong region, people give you funny looks.
The next time you're having a conversation with somebody, check out your body posture and gestures. You may just catch yourself mimicking those of the other person. Change your posture. Watch as their posture changes not too long after. Ever catch yourself speaking differently when talking to certain people? Perhaps you're sounding a little more like them? It's monkey see, monkey do. And I'll tell you, man... ...we really are just goddamned monkeys! That stuff influences the way you interact with people in the future.
Basically, it is the conversations that we have with one another that most shape the way we talk, not what we read or hear. If we all stop calling them e-cigs, then everyone else should eventually do the same. People will come to abandon "e-cig" if more people and businesses refer to them as "vapes."
APV is never gonna stick, though. It's too clunky, extraneous, and esoteric of a descriptor. Again, the simplest terms stick the easiest. You have to retain less information to use them and they can also convey more information with less effort. It's not even a conscious decision. That's why I think people would trade "e-cig" for "vape" with enough exposure. "E-cig" is overly-complex compared to "vape." That's just how the spoken word works. If people hear it called something more abstractly intuitive, that's the word they'll use.
Just call it a "vape" and that's what the word will eventually be! Vaping is becoming more and more visible every year. Most of them don't resemble cigarettes in any way. "E-cig" will have to die eventually.... ...hopefully when people recognize how silly it is to call something that doesn't even look vaguely similar to a cigarette a "cigarette." But most likely it'll be for the same reason dialects exist, which is a start. The connotation will eventually follow.
When I do catch someone calling my vape an e-cig, I politely and sort of jokingly ask them what part of my noisy cricket/snubnose setup looks like a cigarette. Most people, I've noticed, just haven't given it the thought. It's usually one of those "Ohhh, well... yeah. You've got a point there." moments. "Well, what is then?" "It's a vape. I'm vaping."
Had that sort of conversation plenty of times. Never has anyone challenged me on it or thought it was strange. It works because it's more intuitive from a linguistic standpoint. Most of these people only know about vaping through the news. They're not aware of our subculture's preferred terminology at all. They use "e-cig" because that's literally the only term they've ever had to associate vaping to. Give em a shiny, more casual, easy-to-use term and 9 times out of 10, they'll accept it. Just gotta keep your cool and have the conversation with people... ...as many times as possible.
It really is that simple. It's what the news calls us versus what we call ourselves. A lot of people just don't know what we call ourselves so they call vaping what they've seen/heard it called, but I think it's reasonable to assume that they would take a vaper's word on it when they say that's what they are using, if only they knew what we called our devices. "I met someone who used one of those things. He called it a vape."