In old electronics, it's the paper capacitors that weaken with age. Ceramics are essentially rocks and will last forever. Some REALLY old electronics use rectifiers that degenerate with age as well, but it's common practice to replace them with modern cheap diodes as they're made of toxic metals like selenium.
TV tubes are worthless and available by the ton in the basements of most men in their sixties. Most of them were specially manufactured exclusively for TVs, are only useful in TVs, and flooded the market in the 70s and 80s when TV shops stopped working on tube sets because people tossed them and got solid-states.
There are some exceptions. Larger TVs had audio amplifiers that used common PA tubes like 6L6's, favored by guitar players today. 12AX7s are also commonly found in TV speaker amps, and some of the oldies are worth a lot of money to audiophiles. But both types are still manufactured today for those markets.
