I love how the NFL keeps fixing one problem and creating new ones. So instead of finding a way to deal with the one they have years of statistics and research to work on a solution, they choose to go with the knock-off league's idea simply because it solves the problem-of-the-moment, while ignoring that coaches are smart and will find ways to attack the new systems that may include methods that increase injury risk even more.
I would just have the blockers run at an angle (left or right as long as every blocker runs and blocks in the same angled direction) and take out the next guy over instead of the one directly in front of them making them easier to block and push out leaving only one player on the end free that the returner has to beat cleanly.
By attacking at an angle, it removes the need to block and makes it much easier to push them out of the way or at least out of their intended lanes.
If a coverage guy runs head-on into the angle (meaning he also runs at an angle) then either he would make it even easier on the blocker to push him out (if he ran away from the blocker) or he would lose a step because he would have to hesitate to see which angle the blockers were taking (left or right). It would also mean his focus would be on the blocker and not the returner.