it is the software that goes away, not the hardware. As radically different or better software applications come along, eventually the machines are no longer supported by the makers.
I expect some of the machines mentioned here are embroidery machines, I'm guessing that may double the price of a machine?
If I'd never had a machine before and decided I wanted/needed one, I'd define what I want to use it for. Then I'd get the best machine with the least amount of carpola on it, and care for it until it or I died.