What happens to all the CRT's , all the flybacks, tubes, etc

[zenith2134]

So what exactly happens when a major corporation ceases manufacturing of CRT's, etc. . For example, Zenith, what happened to all those tubes, all them chassis' ? Is it possible for someone (a collector, for instance) to purchase a lot of items from a defunct manufacturer? These things are of course NLA, and could proove invaluable in the future to us collectors. Any insight ?