Sadly, I suspect any voter-approved legalization will be much ado about nothing until/unless the U.S. Congress and/or Supreme Court changes positions on this subject. (SCOTUS could do it on their own; Congress would need the Prez's signature, too, naturally).
Don't ask me; ask Angel McClary Raich and Diane Monson -- two California residents and medical marijuana patients who sued in federal court in 2002 in an attempt to preclude the possibility of being prosecuted under the (federal) Controlled Substances Act for receiving marijuana in accordance with California's medical marijuana laws.
The 9th Circuit agreed with the plaintiffs..... but then SCOTUS reversed the 9th.
So far as I'm aware, that decision is still the operative precedent in this area, and it really makes no difference whether any State passes a law explicitly making marijuana use legal (meaning beyond the currently State-law-sanctioned medical use), since any such law would contradict the Controlled Substances Act, and the current SCOTUS roster is unlikely to change that court's position, regardless of how lower courts might rule.
So, bottom line: until/unless the Controlled Substances Act is repealed, or revised to omit marijuana from the list of substances it pertains too.... legal marijuana in the U.S. will likely remain a "pipe dream," so to speak.