I do not know if anyone has lost a trademark over this, but in a practical sense you still need to be proactive--there is no trademark police force that will en

I do not know if anyone has lost a trademark over this, but in a practical sense you still need to be proactive--there is no trademark police force that will ensure nobody uses the domain inappropriately. Consider a donation-solicitation business that takes over abandoned .org domains to collect donations in your organization's name and then keep a percentage. You probably don't want that to happen, you certainly could make a reasonable trademark infringement case, but unless you take steps like sending them a C&D there's nothing stopping them. Even if all they did was put a CNAME for your old .org in that redirects to their own domain they could have a meaningful impact on your operations.