Regarding the topic of resurgence, I believe it could well happen, even to a similar level of the renewed interest in vinyl. There would be enough decent quality, vintage decks out there in dusty cupboards to fill the renewed demand. They are still within the restoration ability of anyone willing to spend some time.
Although these analogue resurgences are still small change in the scheme of things, the whole mechanical feel and cool factor would be driving it as much as vinyl for the younger crowd. There are some countries that have a very vigourous cassette industry and always have, and as long as there are groups of people playing the format, it's still alive, never died, and who knows what might happen. Perhaps a U-Turn cassette deck?
Personally, I'd just love to make a good, driving mix tape again for the car. "Andy Warhol" from Bowie's Hunky Dory would be the first track. It was a fun media to play with in the 80's and I wouldn't have the same access or appreciation for music without it. The digital age talks about accessability, but there was nothing easier than duping a tape or recording from a friend's new record. These days my Wife has an ipod, and so does her sister, but can they share each other's music as easily??