You know, honestly, I see this as a perfect time for consumers to buy iBooks or Mac minis once they're upgraded (I assume) later this year. Both products are cheap and will easily last until the Intel Macs come out. As long as someone doesn't have a pressing need for a lot of power, iBooks and Mac minis will work great as "holdover" computers until the Intel switch. For those who *do* need the power, they're going to buy the fastest Apple hardware, anyway, regardless of whether it will continue to have software written for it for five more years or fifty more years.
Hell, even for "pro-sumers," this wouldn't be a bad idea. I do page layout and graphics work for my publishing company using Photoshop and InDesign on a 12" 1 GHz Powerbook and a 20" monitor. Once the new Mac mini comes out, I plan on getting one and relaxing for the next year or so... Just gonna wait and see what sorts of updated hardware and software come out for the new Intel Macs. Once Adobe and Microsoft (I'm forced to use Office) are on board with universal binary apps for Apple's Intel OS X, I'll decide whether to keep my current hardware or upgrade to the new Intel-powered stuff. Let me tell you how much of a relief it was to see both Adobe and Microsoft up on stage with Jobs... That got rid of a lot of my fears about the switch to Intel.
It seems like so many people are panicking by this switch. The real rub is with the developers. As long as they come along and write these universal binaries, Apple will do fine during the transition. We have all indication that PPC Macs will be supported for at least 4 or 5 years after their run finally ends, so even people buying the very last iteration of PPC Macs will be supported for an appropriately lengthy time after their purchase. Apple's done, in my mind, absolutely everything it can to make this transition seamless. I think they've made the very best of what could have been a terrible situation with what seems to be IBM's lack of dedication to Apple's PPC needs. The fact that Apple's been planning for this potentiality for at least three years is also quite promising. It's good to see honest to goodness foresight from Apple from time to time.
This switch will either crush Apple, or propel it forward. There's massive potential here to gain huge marketshare here, especially when Longhorn comes out and consumers get to compare it with OS X running on similar hardware. Exciting times here, folks. I, for one, can't wait to see how it all turns out.