This.
But in my opinion no need to merge with Slam, the gameplay will just get poorer this way.
To me a better option would be to bring back Heroic Strike to replace FR with a damage ability which still interact with MS.
I would also like them to redesign Rend to be a lot more than a passive dot (Even if it implies to drastically reduce the dot damage itslef)
This can be done in several ways : rage generation by tick , % chance of colossus proc , or any other interaction with a core abilty of our rotation.