Maybe it's because my schema for torrents is dichotomous with licensed uses, but I'm having trouble wrapping my head around this.
Is the distinction you're making here between your proposed 'licensed private tracker' and something like a subscription-based catalogue (à la Audible) simply the way it's distributed (in this case a centralized vs peer-to-peer)?
I like the idea of distributed media networks, but I really doubt any copyright owner would go for a distribution network that they don't have any level of control over. The idea of an 'officially licensed private torrent tracker' seems incompatible with how that industry works.
I'd happily pay for an unlicensed private torrent tracker, though.