They've taken the word 'cassette tape' out of the Oxford English Dictionary. Sign of the times? I'm not sure. Have cassettes really disappeared from our culture? There's bound to be a renaissance just as there's been for vinyl records and film cameras. And guaranteed there's a hipster or two out there, rocking retro walkmans on their skinny jean belts. 
A few years ago, I found two cases of old cassette tapes in the garage. I'd put them together over a couple of decades and I still love listening to them. Well, as long as I'm in my 2002 Pathfinder, that is. That's the only cassette player around my house. Seriously though, mix tapes are part of our fabric, our cultural history. Isn't this a futile attempt to remove it from our lexicon? Tapes are referenced in lots of current books & movies.
“The times you lived through, the people you shared those times with — nothing brings it all to life like an old mix tape. It does a better job of storing up memories than actual brain tissue can do. Every mix tape tells a story. Put them together, and they can add up to the story of a life.”
-Rob Sheffield, Love is a Mix Tape
The mix tape (and therefore read/write cds) might never have evolved if not for the cassette tape. All of a sudden we could record our fav songs from the radio or vinyl, even other cassettes, and then blow off Can-con and payola-driven playlists for our own mix. Even better, we could make a mix tape for someone else, usually someone we're crushing on. A gift that's cheap and heartfelt.
"The making of a great compilation tape, like breaking up, is hard to do and takes ages longer than it might seem. You gotta kick off with a killer, to grab attention. Then you got to take it up a notch, but you don't wanna blow your wad, so then you got to cool it off a notch. There are a lot of rules. First of all you're using someone else's poetry to express how you feel. This is a delicate thing."
-Nick Hornby, High Fidelity
Obviously you can still put together your own mixes using the new technologies but you don't have to work for it; selecting the songs, getting the equipment connected, pressing the play*record buttons at exactly the right moment, stop-rewind-start-stop-play*record....everything to put together a seamless, perfect expression of you - the you existing in that exact moment in time.
P.S. iTunes Genius is the Anti-mix tape. iDeath to creativity.
Anyway if you, like the OED, are done with cassette tapes forever, check out the recycling options available...
BTW, the words added to the dictionary while they were removing cultural icons are sexting, retweet and mankini. psshhtt whatever.