At that point you'll need to design a suitable
replacement; but I
wouldn't
worry just yet. (Hey, leaded solder is still easily available).
For that matter, 100+ year old *new-in-wrapping* incandescent bulbs
are still showing up quite regularly. A friend, a major light bulb
collector, said there are tons of turn of the century bulbs available,
many never used. They are nowhere near rare, at least for Edison based
ones.
Same thing is true about TTL chips or Germanium transistors.
--
Will