I’m unrelated to Hekili’s development. I’m actually one of the developers for HeroRotation.
It is unlikely that Hekili or HeroRotation will die when 11.1.7 drops. Ion has stated that Combat Log API access won’t be going away in 11.1.7 or 11.2. It’s possible that it could happen in 12.0, though. Depending on which API functions they remove/private, it would very likely kill (or severely hamper) Hekili, HeroRotation, a whole mess of WeakAuras, and possibly even Details.
I can’t speak for Hekili’s dev team, but we’re not really looking forward to potentially losing years of development over this.