I'm asking for something in the middle — basically pause a new law from coming into effect because enough residents have given signatures for a proposition that would invalidate it. What I think you're describing is invalidating it after it comes into effect. It would seem reasonable to have an avenue for pre-empting a very unpopular law (passed by legislators and signed by the governor) from coming into effect, given that the proposition system already gives residents a way to later overturn it.