As @Kevin Keane points out here (and in the comments section above), Windows 10 now clobbers mDNS port 5353 with a service that only works for modern Windows apps. So to let Bonjour back onto the port, the windows mDNS service must be quashed via the registry edit described in the link above.
Instead of the registry edit, the group policy editor can be used:
- launch gpedit.msc
- Navigate to Computer Configuration > Administrative Templates > Network > DNS Client
- Enable the "Turn off Multicast Name Resolution" policy.
I didn't have to reboot.
Caveat, I already had both iTunes and Bonjour Print Services installed. Simply uninstalling Bonjour Print Services and reinstalling didn't work -- I had to go into add-remove programs, uninstall both Bonjour and Bonjour Print Services, then reinstall Bonjour Print Services, before pinging .local addresses started working again (virtualbox host-only linux guest with avahi-daemon running). I think this is because my "Bonjour Service" service was tied to Bonjour, not Bonjour Print Services, and it wasn't re-registering itself.