Personally I don't think so, at least not entirely, unless something changes drastically with ARM technology in the near future.
What I could see happening is a two-tier product lineup with ARM powering the low-end MacBooks and Mac Mini, and perhaps even a low-cost multimedia iMac that would be TV-sized.
ARM could allow OS X to run in a whole array of new devices and applications which could extend Apple's reach into new markets.
But if you think of the high-end workstation market, which is what a lot of people use their iMacs and Mac Pros for, an ARM chip just isn't going to cut it, and nobody really needs the ultra-low power consumption that ARM brings in those environments.
I believe Xeon chips will be under the hood of high-end Macs for a long time to come, and as long as that is the case, Hackintoshes should remain relatively easy to build. If on the other hand, Apple decides to go ARM at the low end and develops an entirely new architecture to truly differentiate their desktop machines at the high end, then all bets are off - that will require quite an investment to develop, however.