So just target Lion and above, that's 54%, which might sound small, but it's tens of millions of users. Mac software houses thrived in 2005 with 1/4 the user ba

So just target Lion and above, that's 54%, which might sound small, but it's tens of millions of users. Mac software houses thrived in 2005 with 1/4 the user base that what that 54% represents. That's true. Though it's still way better to support 72% in one API than 54% in two slightly different APIs. That said, I highly doubt SL is 35% still. I think you're right. Those 32bit Intel iMacs are probably on their last legs at this moment. In one year, I predict Mavericks may have 80% or even higher market share, comparable to its remote cousin iOS7's share on iOS devices.