How long should components last?

In contrast to the AV receiver experience I wrote about, in 1980 I purchased a new Mcintosh MC2125 power amplifier.  In about 2005, I had it refurb'd with new caps, an LED replaced, and a few other minor items replaced.  The cost was very reasonable.  In 2022, I traded that fully functional and cosmetically almost pristine amplifier for a newer amplifier.  Most of my electronic components (Rogue, Odyssey, Lounge Audio) were made here in the USA, and they seem to be built for the long-term.

I have a variety of components that I bought new, in 1975, or earlier, that are still operating in my vintage system after refurbishment. My first ARC amp from that year, a Dual 75a, is still in good fettle, but dormant- I would recap it, have a full set of older replacement tubes and a few other odds and ends that I bought from ARC years ago (like the barrier strip terminals, which break). 

The amps currently running in my vintage system were built in 1959 and 1961. They were refurbished twice, most recently by the late Bill Thalmann. 

I expect a lot of this gear to last a lifetime. I’m now in my 70s, and though some of the gear was more expensive than beer budget at the time, we are talking about decades old expenditures (leaving aside routine maintenance, and of course, sourcing good tubes, which is a PITA). To me, that’s a better expenditure than replacing consumer electronics every ten years. Then again, when I bought a lot of that stuff, it also wasn’t oligarch money. I was still in college when I bought that 1975 system and paid for it out of savings because I also worked part-time. I don’t know how that would work with uber-priced components today. 

My Lamms were purchased in the aughts, early serial number ML2s. They have been serviced over the years, but nothing drastic-- in fact, when I lived in NY, we’d drive them over to Deep Brooklyn. Now, I’d have to pay for air freight from Texas (to Florida, where Lamm relocated after Vlad passed). But still- those amps, as Vlad once told me, can last a lifetime. 

Vintage guy here, my pre & power amp are 50 years old, have been refurbished by me 2 years ago, expect this stuff to outlive me.

Some of the new surface mount gear, with cheaper power supplies and op-amps, is mostly disposable. Sadly think streamer are a disposable product. As soon as the software leaves the app store, they are useless. 

If taken care of, most things should last at least 10 years. 

The transformer failed in the DAC and as the european manufacturer had discontinued the component it had to be made from scratch in Italy.

How do transformers fail? Aren’t they simple windings on 2 sides with some winding cores?  Do the cores get damaged?  I’m trying to understand if they wear out from usage or a design flaw

I can't say my gear has original parts, but virtually all maintenance I've done is preventive.  I have tube amps ranging from 60- 70 years old, a tube preamp (SP3a1) that is 50 years old, and also have CD players that I bought in the 80s that are still working fine without any updates (but probably need them).  A solid state power amp from 1974 that, when adjusted for today's dollar value, cost $8500.  Also have newer tube gear from the turn of the century that is still original, and when I see/hear signs that it's time for a bit of updating, I'll do it.  As for gear purchased new in the past 5-10 years, only one failure, and it was a cheap DAC under warranty.  Based on all I've just said, the answer to your question is very clearly no.