I highly doubt it. I think if smoking is ever completely phased out, it'll take much longer than 50 years, but I honestly don't think it will ever be 100% gone. It's too easy and cheap. You can make a joint or a cig with scraps. You can't make a quality vaporizer the same way.
I think the minimum amount of time it would take for smoking to die out past 95% (of everyone who either smokes or vapes), would be however long until everyone who currently smokes, or is a child of smoking parents/has smoking friends, dies off. That way vapor will be what kids are raised seeing as the "norm", instead of just something new that is here to replace smoking.
It's kind of like saying "will anybody write and mail letters now that we have typewriters-->computers". There are a lot of people who are used to it, that will always prefer it over the newer, more efficient method.