Clarification and emphasis on the "blindside block" is a good thing and should help avoid unnecessary injuries and problems, however it hopefully will not dramatically change the nature of legal, and appropriate, contact related to the game, which is still a game involving physical, sometimes severe, contact.
The game has experienced decades of intensified focus on "blowing up" unsuspecting and unprepared opponents to promote highlight films and crowd reactions, producing the inevitably predictable escalation to dangerous excess. This rule, and the coaching that will hopefully accompany it, is a significant step towards reducing, and hopefully eliminating, this unfortunate excess and returning to the acceptable objectives of the game.
Judgment, and positioning to be able to see the entire contact sequence, are likely going to be key factors in determining the necessity and appropriateness of the specific contact (as each contact will continue to be unique) and whether the contact observed was, or was not, excessive.