"In a few years," Chrome and Firefox will have support for source maps. The average CS developer will be debugging in CoffeeScript, not JavaScript. The original author's argument is much weaker when this feature is considered.
The author of the people-will-forget-JS-in-the-future premise is specifically referring to the future. CS specifically solves a present-day problem--ugly JS syntax.
In the case that your prediction comes true, his (and my) concern that people need to know JS will probably not be as much of an issue. But then again, he'll be right about giving up on JS, and debugging in IE will still be a monster.
