There is no technical reason (in that they could technically keep 32bit support) for Apple to drop 32bit support since the x86 CPUs they rely on support them - i've heard that there were some architectural reasons with Cocoa (i think) that made it harder to do that, but they came up with that architecture themselves while knowing that people have invested on 32bit support. They knowingly decided that making the work easier for a handful of people was more important than the many thousands of applications that would break - they put themselves above their customers.