The short answer is yes. There is a huge demand for WordPress developers.
Suppose you are one of those developers who know only a basic of WordPress and plugin development. In that case, you may feel everything that one needs doing in WordPress can be done via a plugin, and so why will anyone need a WordPress developer.
The reality is, as the site on WordPress grows, there is so much that customization that client needs that there is a massive demand for quality WordPress developers.
Furthermore, to develop those plugins, we need developers.