I find this very interesting, especially combined with the changes to Dark Command, Reckoning, Growl and Taunt. All of these abilities will now not only force a target to attack the tank in question, but will also increase her threat by 200% for 3 seconds. This means that, even if you are tanking a boss or mob that you already have threat on, these four abilities will still increase your threat overall when used, meaning that if you hit a taunt while tanking it will still have a positive effect on your threat. It's worth noting that hunter pet Growl works exactly the same - hunter pets will also get the extra 200% threat over the three seconds.
We're clearly not even remotely done with tweaks and fixes in patch 5.4, but by themselves these changes suggest that tanking is definitely going to see its fair share. The change to taunts is the biggest change to how taunting works that has ever happened, and the inclusion of Riposte goes one step further towards making avoidance also provide threat.