Time will tell.
As we all know making the switch to vaping is not just a simple switch. It's a different experience. Bet most of us coughed quite a bit our first few vaping draws too. That can be a turn off to switching that it is not an exact experience replacement, but maybe it's also why it is easier to stay away from smokes once your brain makes that transition.
I don't know what is going to happen with IQOS. Perhaps being too much like a smoke, and being kind a hassle to use (cleaning required, puff count and timer in the back of the mind, needing to recharge the pen in the holder, butts to dispose of, just using it requires more manuals steps to light up then a smoke or a vaping rig, etc.), well I can see how people could eventually just give up on it and go back to smokes, especially if using the device costs about the same as smoking. That has been another advantage and incentive of vaping, affordable e-juice.