Adding my thoughts for the best little machine I ever had, both 2010 and 2012.
My 2012 doesn't need replacing, though I wish battery life were better, but I'll be moving on to the rumored Samsung ChromebookPro that will replace my 2012 11" MBA and my 2012 galaxy note 10 tablet in one machine. I still need something portable enough to carry around in my purse for all our travel (which both my current devices together currently are) and the Chromebook will give me more ports than the new 12" MacBook, including a micro SD port.
I expect my 11" to keep on chugging for a while, but as I prepare for the inevitable transition, his days are surely numbered.