I'm terrified of not being able to find old USB cables.

My D2A converter I use to route TV audio to a small amplifier died. It was cheap, but decent. I wanted another cheap one. I had trouble finding any. Finally, I snagged a pair on Amazon/eBay, but it used ancient USB connections. Luckily, I had old USB cables, so I'm good. But what will I do if the USB cable stops working?