Extension:Comments, like other social tools, has literally been maintained for over a decade ā mostly by a small team of volunteers, including me, since 2008. I don't have a crystal ball so I'm not able to accurately predict the future, but currently there are no plans to stop maintaining Comments and/or any of the other social tools. Furthermore I'm confident that even if I need to step down as the maintainer of the social tools group of extensions, someone else would fill in the void, given the popularity of these tools.
If you encounter any issues, bugs or need help, please don't hesitate to post on the extension's talk page (for general issues) or file a task on Phabricator (for software bugs).