The Walkman's retirement wasn't quite the death of the cassette tape, but the format's final days aren't far off: Sony's calling it quits on the tape recorder. Final shipments for the company's TCM-400, TCM-410 and TCM-450 cassette recorders are due early next year, marking the end of the product line. Despite the shunning of magnetic tape from Sony's portable line up, the company still has a slot in its heart for the old cassette, and will continue to sell boomboxes with CD / tape deck combos. Even so, rewindable media seems to be on its way out the door -- maybe its time to build a better mixtape.