There's no future for privacy coins. Let me explain why:
The primary goal of cryptocurrency is decentralization and full ownership of assets for each individual. But that doesn't mean that full ownership must be anonymous.
Transactions on decentralized blockchains must be traceable to ensure public transparency and/or manually verifiable for specific purposes. Untraceable transactions are easily misused for various crimes, from money laundering to human trafficking.
That's why a purely anonymous cryptocurrency will never be acceptable to a human civilization that must uphold laws and norms. Therefore, I believe any cryptocurrency based on anonymity will not last long; its price will fall sooner or later.
Privacy cryptocurrencies will only be championed by those involved in crime and illicit businesses.