Maybe I'm just being a simpleton.
Section 7.09 of the rules covers interference. Here's rule 7.09(d): "It is interference when any batter or runner who has just been put out hinders or impedes any following play being made on a runner. Such runner shall be declared out for the interference of his teammate."
From the moment the runner approaching second base on a potential double play is out he can not hinder or impede the defensive player. At all. This means no take-out slide. Can't this long-existing rule simply be enforced?
My thinking is that that part of the rule was never enforced and what this new rule is trying to do is make sure slides like Utley's don't happen. I don't think the umpires will be too aggressive but we'll see. I don't think this changes much since slides like Utley's were pretty rare. Where we'll end up seeing controversy is if/when umpires call interference on plays most of us think were pretty tame. We say some problems with the 'catch' rule implemented last year, IIRC.
Generally, I don't think this is a big deal. It gives some consideration to player safety, doesn't alter the game much and will probably be forgotten fairly soon. I admit, I loved the Hal McRae slides but those have been out of baseball for 30+ years. The game is fine. I don't think we're going to be turning into the Japanese game where this is no contact at second, but we'll see.