Sad times, indeed. Voter ID (tied to citizenship - so Real ID or passport + driver's license) and perhaps notarized ballots (where the notary is free for a ballot but they must confirm the ID in the same way as in-person voting).

The other underlying issue is that there is no way currently to confirm that your actual voting selections were recorded correctly, nor anyway to tie the person to the specific ballot. They want to avoid that because they don't want people to sell their vote, but it also makes it much easier to audit the vote and ensure accuracy.