i don't think sasuke is going to go mangekyou yet. even if he did somehow manage to kill naruto. he hasn't gotten his last dot yet. so we know that there is much that he hasn't developed yet. maybe level 2 curse seal will help him develop his 3 dot.

Also i would love to see the look on everyone's face when they hear naruto beat the crap out of sasuke and broke every bone in his body. especially sakura's