Put yourself in Apple's shoes: you've just smashed one out of the park with the iPod. You spent a few years working on it, polishing it, developing generation after generation of updates that instantly make the previous version look old 'n busted. After a slow start, you eventually take the DMP (Digital Media Player) market by storm, beating out a few major companies at their own game. Six years and a ton of 3rd party accessories later, you are the king of this particular domain, with what appears to be nary a formidable challenger in sight.
Next: imagine that, after introducing the iPod and giving it that nudge it needed to skyrocket in popularity, you embark on another project, spending at least four and a half years developing a killer mobile phone + DMP + internet device the likes the world has never seen. A gadget so cool and anticipated that it is not only shaking up the mobile phone market, but it single-handedly drowns out the entirety of CES during the week of its introduction. A key factor here, oh reader who is momentarily in Apple's shoes, is that the mobile phone market currently speaks in the mouth-watering language of 'billions,' while Apple's iPod sales - impressive as they may be - are playing in the kiddie pool at 'millions.' Whether you want a mobile phone packed into your iPod or not, you can't ignore the fact that the mobile phone market makes iPod sales look like the Zune's on a good day.
Now, keeping in mind these numbers, a sales pie the likes you've never seen barreling straight for your revenue stream and investors practically wetting themselves while dreaming of iPhone-shaped dollar signs at night, are you really going to cannibalize the profits off your most anticipated device of all time by yanking out a key component (the phone) and selling it for $200 or $300 less? Before you skip what little is left of this post to try and answer that question, let me save you the trouble: the correct answer is no, no you wouldn't - under penalty of death.
Unfortunately, those who are holding their breath for an iPhone-like iPod should probably alert the paramedics sooner rather than later, because you're likely in store for an asphyxia-related concussion (from, say, smacking your head on your desk once you pass out). Unless the iPhone somehow turns out to be a colossal failure, all signs point to the iPod not receiving any of the iPhone's slick UI anytime soon; not for at least a year or two, or possibly longer (and even then we might be subject to the fated Newton Syndrome, where Jobs banishes the design to the Cupertino Dungeon, never to be heard from again). After all that work, Apple is going to want - nay, need - to squeeze the iPhone for every penny they can, especially in the incredibly competitive market of mobile phones where look-alikes are already cropping up.
As sad as it may be, it really doesn't seem like the iPod will become the instrument of the iPhone's destruction. If you want to get fingers-on with your iTunes media, the iPhone will likely be your only shot in the near - or possibly far - future.