From what I've heard, that seems to be the case. I suppose that's part of why legit Walkmans are going for so much now. I love cassettes and it would be cool to have a good portable tape player again, but it really can't compete with my phone. Unless we go back to carrying around all the individual things a phone can do. It's tempting but just not as convenient.
I still play around with tapes at home. I have a modded player with speed controls, a couple of decent tape decks, and a 4 track recorder. I have a couple of loop tapes to play around with too. But yeah, as a portable music format, not sure I want to go back to that.