The classic and the Touch are totally different. Surely theres room in this world for both of them.
There are still alot of traditionalists out there who prefer the click wheel. So it wont vanish as soon as you think.
There really isn't, seeing as Apple is phasing out the former.
Cutoff at 64GB is a little premature, so I'll say that the iPod classic will be killed when the iPod touch hits 128GB.
And the "traditionalists" will just have to change, because Apple doesn't care.
in my opinion i think over time Apple will take more of a spotlight on the Touch over the Classic, however i don't know if they would wipe out the Classic as a whole within the next two years.
Apple is probably still making money off of the Classics, maybe not as much compared to the Touch's because with the Touch you have the option of buying software updates/applications and whatnot, but over time the Classic will probably be gone. i could be wrong however.