What audio components are heirloom quality?

Great and commendable plan. Keep it simple! You don't know the extent to
which your child will want to play around with the technical or tweaky part of
the hobby. You don't want to overwhelm him/her; you want to promote an
appreciation for music and good sound. Personally, I would do great
sounding (and great looking) small speakers like Sonus Faber
"Guarnieris". You mentioned "nostalgia": make sure
nostalgia does not equal obsolescence; so, stick with companies that will
be around in twenty years. An Audio Research or Conrad Johnson tube
integrated amp (phono stage of course). Include a supply of
replacement tubes. And of course, a turntable. I am tempted to say LP12,
but simple is the goal. VPI Classic is a winner.
Whatever cartridge you choose, make sure you include at least one spare.
As far as digital goes, who knows what will be relevant in twenty years?
Leave that one to him/her. Good luck. Lucky kid! Good Dad!

None are. Unless your children may want to display under glass, the relics of a bygone age.

Instill a love and appreciation of good music. That will last a lifetime. It will enrich their lives beyond measure.

NO equipment will withstand the march of technology and social change.

One member on audiogon, who is a lawyer, did a lot of estate stuff, once posted: you will be amazed how often one man's treasure is another man's junk.

My parents never had high end gear, but they left me with a love of music. Music was always in the house. Piano, records, and singing. I still thank them for that.

Cheers

Rok2id:

+1

"My parents never had high end gear, but they left me with a love of music. Music was always in the house. Piano, records, and singing. I still thank them for that."

Amen to that Rok2id, me too.

IMO a well preserved LP (ex. Blue Note, Columbia 6-eye, Mercury, etc.) of a great recording is a work of art- the cover design, the notes on the back, etc.
it's so satisfying to look at and read the cover information while getting into tbe
tracks. And don't forget the fold-out albums either, and ones that came with booklets, catalogs, "zippers"...