My iPod froze up over the summer. I think I had dropped it a few too many times. Nothing I did could make the flywheel work. I used frequent player points in my Pokerstars account to order a new one. After charging up the new one, I charged up the old one just to see if it would budge. . .and it did. Now, I am using my old one regularly. I may keep one in the car and one with me or something. I don't know how the old one came back to life. Apparently, I am the only person who likes the old classic model. You can almost not find any classic cases at Office Depot, Staples, Best Buy or Radio Shack. They mostly carry touch model cases. When is the touch going to hold 100 GB so I can carry my whole library on one?
Well, considering the iPod Touch currently tops out at 64 GB of flash storage, I'm going to say one or two more generations, depending on how the price of flash media stands in September 2011. Actually, because the third generation had a 64 GB model as well, I wouldn't be surprised if the next one came with 128 GB. The price of the flash memory is going down, so yeah, I think the next release in September 2011 will probably have a 128 GB model. However, so far as I know, there are a couple flash based players out there that already have 128 GB of storage.
It will probably be a while until the Touch holds that much. Like william said, 1 or 2 more generations would probably do it, but there's no guarantee. If you still want to use your iPod Classic, you can get cases on Amazon and such.
Actually, it's up to 64 GB for this generation, which is reasonable (albeit expensive). Hard drive based players are still the way to go right now if you want a lot of storage. If you're looking for a touch screen player with over 100 GB of storage, have you checked out Archos?