You need to rephrase your question. WordPress doesn’t have anything to do with Web Design 🙂 But, it might have an influence on web publishing.

WordPress has dominated the CMS industry in the last decade. It’s easiness to use, the comprehensive themes and plugins options and the smooth extensibility when needed are some important factors contributing to its success.

But the future is a bit blurry, though. Security and performance issue is a couple of points where WordPress doesn’t seem to be proficient
WordPress will probably still dominate in a couple of years and will remain a viable option in the next decade to build a website. But at the same time, a particular kind of alternative is flourishing and will be soon mainstream. It has enough value to dethrone WordPress.

SaaS CMS, like ButterCMS, is pretty hot right now. They seem to be a bit overpriced, though. But they are something that will redefine how CMS work and perform.

And static websites generators, like Hugo and Jekyll, are gaining popularity, and will soon be manageable by regular users.

Keep on watching these two options, I’m making my bets that in 3/4 years from now, WordPress market share will be comparable to these two 🙂