I'm a little surprised ours don't support it. I guess I can see why Apple wouldn't want to officially support us given they finally have a new Mac Pro out, but as long as we have metal cards, I'm not sure what is stopping us from installing it. 2012 Macbookpros etc and 2012 iMacs are all compatible, what does there's have that we don't?
I wouldn't be surprised if "unofficially" we're able to install it. Although we won't get anymore firmware upgrades, but I appreciate Apple for still upgrading our firmware so far.