To be precise, anyone is free to contribute to https://extensions.xwiki.org/xwiki/bin/view/Extension/Ideas and it’s improved by the xwiki.org community. It’s not discontinued.
It’s true that XWiki SAS (one of the main sponsor of the xwiki open source project) was originally sponsoring its development but has decided some time ago to propose its own improved version (which is not free).
See Moving some extensions as paying extensions for more context.