It is just like new, granted no motor damage.
The thing is, "most" subwoofer soft-parts are chosen based on the motor design and usually optimized for the advertised application.
Can you slap in some other parts? Sure. Is this necessarily ideal, probably not. Sure you can put in a different type of coil (copper, roundwire, flatwind, 4-layer, 8-layer), different spiders (progressive, linear, material, amount), type of cone (pulp, nomex, etc), surround (foam, tall, rubber, etc)...
But you can't just choose randomly, and it must be matched to your motor/gap. And even in the end, it may not perform as well. But you can create a fully functional, great woofer with better parts as well. (Improved power handling, response, etc).
So, it's at your own risk. :shrug: