It sounds like really open to interpretation according to the early word on it. Can an infielder still drop his knee in front of a base while fielding a throw. Can the catcher still field a throw in front of the plate but leave his leg draped in the baseline? If the catcher is blocking the basepath and you try to slide, then what? Catcher gets fined, but your team gets an out because you wouldn't bowl him over? Same in reverse? You start with banning the actually collision, which is always instigated by the runner, but then you add some opportunity to call interference if a catcher blocks entire path or something. Of course, umps won't be able to not screw up.