If finalized, the repeal would void the core legal predicate for existing and pending federal greenhouse-gas rules, forcing any future climate regulation to rely on new statutory authority or a rebuilt administrative record. Regulated sectors (power generation, vehicles, and major industrial emitters) would face a near-term compliance reset as Biden-era climate rules lose their foundation and enforcement posture shifts. The change also concentrates the next decision points in litigation and state-level regulation, increasing the likelihood of a fragmented compliance map across US jurisdictions.