Static WordPress is possible - you can generate a static replica of your WordPress site and deploy that via CDN. There are some plugins that help you do that (Simply Static, WP2Static) but you need to also configure your whole infrastructure when using them, and the build process can be long and painful.
There are also managed services for doing this that take care of everything for you, from the WP hosting env, to the static hosting and CDN, along with replicating certain types of dynamic functionality on the static site like forms and search.
One example of this type of managed static WordPress hosting service is Strattic: https://www.strattic.com.
Have you seen Strattic? It's a static hosting service for standard WordPress sites (i.e. monolithic WordPress as opposed to headless WordPress), so the time has arrived (unless you meant "freely" as in "free beer" and not "without limitation). https://www.strattic.com
You could use WordPress as the CMS (it's an excellent WYSIWYG editor) and then publish the site as a static replica using one of the tools and solutions available for turning WP into a static site generator, like Strattic https://www.strattic.com.
WordPress is pretty good until you start adding loads of content because it's built-in API is REST. You can get a lot more out of a plugin which adds a GraphQL layer to WordPress, but I have experienced issues with that before because GraphQL is strict on types whereas WordPress (based on PHP) is dynamic, so if there's a type mismatch (say for example someone has a number as a slug, where elsewhere it's a string) the GraphQL layer can break unexpectedly.
You can try Strattic - it turns WordPress into a static site generator so you can use page builders etc. as usual, and then in one click generate the static version of the site. https://www.strattic.com
Many people in the comments recommended using WordPress, and for good reason. Your client can manage their content on their own, and WP will be around for the foreseeable future.
If you want to use WP as usual and get a headless output in one click that even your client can generate, check out Strattic: https://www.strattic.com (Disclosure: I'm from Strattic).
Chris: I wonder where headless WordPress will land. And by “headless” I mean only using the WordPress admin and building out the user-facing site through the WordPress REST API rather than the traditional WordPress theme structure.
Is it… big? The future of WordPress? Or relatively niche?
You could check out Strattic which gives users the best of both worlds - edit your site as usual in WordPress, and click a button to deploy a static, Jamstack version of the site. All the power of WordPress with none of the headache. https://www.strattic.com
WordPress is a nightmare because of the issues surrounding speed, security and scalability. But if you use a static WordPress hosting solution (like Strattic for example - I'm the CEO) that solves all that, so you can benefit from WP's robust CMS while enjoying a perfect, static output. https://www.strattic.com
I totally agree. It's so important to own as much of your content on the web as possible. That's why CMSs like WordPress are a great solution. I know WP has lots of issues, and that's why we created Strattic: static and headless publishing for WordPress websites so you can easily and quickly create content, but not worry about security and performance. https://www.strattic.com
There are also managed services for doing this that take care of everything for you, from the WP hosting env, to the static hosting and CDN, along with replicating certain types of dynamic functionality on the static site like forms and search.
One example of this type of managed static WordPress hosting service is Strattic: https://www.strattic.com.