The future of htmlimport - will my app stop working in 2019?

There is a warning shown in my Chrome 70 browser’s developer tools console:

 HTML Imports is deprecated and will be removed in M73, around March 2019. Please use ES modules instead. See for more details.

Will my vaadin flow application stop working because using the @HtmlImport(...) annotation?

Your Flow app will continue to work but will use a polyfill for the HTML imports in Chrome also (it does that in other browsers today already)