The short answer
Volatility forecasting is not useless for HIP-4 markets, but it changes meaning. In a continuous market, volatility often describes the expected dispersion of an ongoing price process. In a HIP-4 market, the more useful question is often how violently odds can reprice as new information arrives before settlement.
That makes volatility less of a standalone alpha target and more of a context variable for liquidity, timing, sizing, and how much trust you should place in the displayed price.