You can only vote while you you can't see scores. If you toggle "show scores" you lose your ability to vote in that thread forever.
This eliminates the snowball issue, while letting those who want to quickly skim have a good way to do so.
Also someone will probably end up writing a browser extension to show the comment scores automatically on every single thread using information from another account.
In a similar fashion, nothing prevents someone from writing a browser extension to add comment scores back today, e.g. http://hnpoints.com/ ; The scores aren't official, but they serve the same purpose. Most people aren't going to install a browser extension. Of course, some will. But most people will just use the site as-is, out of convenience.
My personal opinion is to let it run it's course. RiderOfGiraffes at the beginning of this whole dilemma posted single page mirrors of the frontpage of HN taken once a month (or week) for the past few years. Looking through that, specifically the comments, the only difference I saw was that the commenters were much more buddy buddy and on a first name basis. Unless PG wants to redo the entire site and use some sort of invitation system much like a private BitTorrent tracker uses, I highly doubt a public community site would ever "avoid the Eternal September". Open registration means anyone can come in and be themselves. This will always change the community. Moderation can only go so far. If further action is desired, further action must be done.