If you're using a modern Mac today, you're essentially running a modernized version of NeXTSTEP, so actually it's NeXT which has survived by 'reverse-acquiring' Apple, and the original Mac has joined the technology graveyard along with Amiga, Atari etc...

...or actually... modern Macs are a NeXT/Archimedes hybrid - the software comes from NeXT, while the hardware is of Archimedes heritage ;)