Well, it’s possible.
I don’t think there is anything preventing a state to award all EVs to the winner, nor dividing them up based on vote percentage.... Federalism at work. Nationalism isn’t what the constitution demands in all issues, actually, only a few enumerated powers.
Most states are winner take all.
“it could virtually invite Republican-controlled legislatures to rewrite centuries-old laws ensuring that the candidate who gets the most votes in a state gets its electoral votes”
What the article is saying is that state legislatures could end the winner takes all electors and move to split electors by vote proportion like Nebraska and Maine do.
This would make it significantly harder for Dems to cheat to win since they currently cheat in deep blue cities to outvote the red rural and suburban areas.
This is a nonsense headline, of course.
It COULD decide one way, or it could decide the other. Taking the case doesn’t imply anything.
More importantly, it wouldn’t upend anything. The question comes down to whether the courts in a state can impose their own rules about election conduct. Rules that aren’t in the statute. Also, more marginally and unlikely, whether if a legislature chose to assign electors directly, would it need the governor to agree.