The guide is based on historical product cycles. With the iPod classic, it's hard to say. On the one hand, it's unlikely Apple would have a large market for an even bigger than 160GB one. On the other hand, they could do all kinds of other things, like replace it with a touchscreen / hard disk iPod. I'd guess at some point they will do this and ditch the famous scrollwheel (maybe not for the nano or shuffle, though). But it's hard to know. They could also do a variety of little things like... release it in colors, make minor changes in battery life, screen brightness, thickness, etc, or reduce the price by streamlining (e.g. removing the 80GB option and selling the 160 at the current 80 price).
If you were buying for yourself, I'd suggest that you get a refurb or even a used one. I'm not sure the extent to which those are options for you for buying a present (depends on the circumstances).
Since you are buying for someone else, are you fairly sure that the Classic style is what they want? The Touch seems to be a hotter commodity / get more attention at this point.
FWIW my disclosure: I have three iPods currently, having purchased a total of four ever (my first broke after about four years). My iPods are a 4th generation iPod Photo 30GB, a 2nd generation iPod Nano 2GB Silver, and an iPhone 8GB.