It’s just a waiting game at this point.
VGC is reporting that fans have discovered what appears to be a placeholder Twitter account for Super Mario’s 35th anniversary, which was registered earlier this year under the name of ‘AAAAAAAAAAA’. The password reset links to a Nintendo Japan email address giving weight to the rumour.
Nintendo has already kicked off celebrations for Super Mario’s 35th Anniversary through the announcement of a Uniqlo clothing line as well as the LEGO Nintendo Entertainment System, but they’ve never really announced anything for the special occasion on their own channels.