While I can't claim to speak with authority on this matter, a far more likely outcome would seem to be :

  1. Yahoo sues Facebook  
  2. Facebook settles for some large-though-not-crippling amount of cash  
  3. The public forgets and moves on, since no-one's actual day-to-day user experience is affected (and we collectively do lack a bit of an attention span)  
  4 [epilogue]. Companies are further incentivized to leverage patents in the pursuit of financial gain

Of course, MC knows this, which is what I'm sure prompted this post to begin with.