Indeed this is a good thing not just for them, but for developers already doing this. As small businesses opt for these build-your-own-website services their competitors , particularly those who have little-to-no knowledge of design/UX, may decide to up the ante and hire a developer.
I've launch ~25 custom-theme WordPress sites for clients over the past 6 years and there has yet to be a shortage of clients who are willing to pay for someone else to deal with it (and even maintain it long-term).
My most recent project, approved just last week, is exactly this: a client with a SquareSpace website who needs to step-it-up as a result of the increased local competition, so we're doing a full redesign and building on WordPress.