+ Hidden service in TOR
+ Tracker/forums hosted in .ru (Nobody took down libgen or sci-hub yet and you can bet many have tried)
+ Decentralized software solution that can serve metadata and forums over the swarm in addition to torrents.
The first solution forces TOR on everyone, not ideal.
The third solution is not quite there yet, but should be the future.
So, at the moment, I would say that if you're not hosting your shit in Russia, don't even bother ...
The only reason other private trackers that are hosted in western countries have not been taken down is that most of them are too niche for any special interests to bother. If/when that threshold gets crossed, as it was for what.cd, they will all be destroyed. This should provide a powerful disincentive for people to contribute their time and resources to such communities, unless of course they implement any of the solutions I mentioned. Alas, most private tracker operators are clueless idiots on a power trip and lack the vision (nevermind the technical expertise) to deal with or implement proper solutions to well-known issues.
Look to the russians for inspiration.