I don't think manufacturers are required to keep making parts for any specified amount of time. It's not a regulated market. I bought a Viking in 1995 and there are cassettes which you switch out for different stitches. But they no longer manufacture the cassettes and told me to try to find them on ebay.
It seemed like a lot of money to me in '95 (close to $2,000)for that machine but apparently they want you to buy new machines more frequently than I can afford.