OMV's WebDAV plugin relies on SabreDAV. In April SabreDAV's developer stopped supporting SabreDAV. Since no other developer has stepped forward to take over support, this implies SabreDAV is essentially petrified in its current version. In turn, this implies OMV's WebDAV is too.
WebDAV is built on http, and OMV uses NGNIX for http services. According to Wikipedia, NGNIX has "a very limited optional WebDAV module" (which is not automatically installed). So even if OMV started using NGNIX WebDAV, it's not clear that this would meet users' needs.
OTOH, according to the same Wikipedia article, Apache provides WebDAV modules.
So this is appears to be a case of one domino affecting others. Moving forward, what's the best way for OMV to provide WebDAV services that will continue to be supported?