"there'll be a lot of web developers suddenly out of work"
That seems rather doubtful. There's a lot more to web development than just arranging the visuals. This tool seems more suitable to allow non-web developers to design simple pages, and to relieve real web developers of the tedium of designing simple pages.
"Better learn some real programming languages guys..."
It sounds like you're confusing two different professions. While there is a bit of overlap in the Venn diagram, web developers and software developers are two different skillsets that require two different ways of thinking and working. Witness how terrible most software developers are at web development. Web developers aren't wannabe software developers who couldn't be bothered to learn <insert your favorite language here>.