My money on the first big causality of the new gTLD program is http://Rightside.co
Looking at ntldstats.com, it would appear that they can't manage to break +250 new registrations per day for about 40 domain extensions that they own and operate. Even worse, it looks like they have been going negative on new registrations now: https://ntldstats.com/registry/Rightside-Registry
The user interface has also gone to shit on their site Name.com. I'm a developer and can't for the life of me understand their backend anymore. Google Domains crushes them design-wise.