This will probably seem like heresy to some, but as my old cassettes get digitized, they are being re-assigned to wherever the Portland City Dump is located. I've got - literally - between five and ten thousand cassettes, and I've been dragging them around for years. Moving across the country from Minneapolis to Portland convinced me that I'd better give the task of conversion my best effort, and then be done with it. The .wav files are all painstakingly examined for flaws, notes are compiled in .txt files, and the audio is then saved to level 8 .flac files. I'm not even burning CD-Rs anymore, except for bands I've recorded who still like that format.
As for passing the tapes on to someone else, that just seemed like a good way to pollute the pool somewhere down the road. I suppose that will still happen, as I share the digitized files with people, since everyone and their mom is a "re-master" expert these days, but my intent is to simply preserve and share the original, raw files. What happens after that, is fair game for anyone, I guess. I feel bad enough about dumping all this plastic out there, but really, the artifacts themselves only have as much value as someone wants to put on them. I've got the music in a much more accessible form now, I think.