I you talk about pure mechanical cameras, then maybe yes. But digital ones or even those with a minimum of electronics (if they need a battery) won't keep 50 years. Be happy if they last 10 years.
And why are electronic film cameras like the Canon AE-1, Nikon FE, Pentax ME and LX, Nikon F3 etc, which are now even in 35 - 39 year old range, still working?
Why has the F3 the reputation of being one of the most robust cameras?
Why has my camera repair man much more work and problems with the Nikon F2 compared to the F3?
Film cameras with electronic components have proved for decades now that they can last a very long time.
And even if an electronic part may fail after 30-40 years, then replace it with a part from a donor camera.
It's the same way my camera repair man give new life to mechanical cameras. No difference at all, because the spare parts problem is a general problem for very old cameras.
I am into photography for about 40 years now.
I have never had a single failure with any of my electronic based film cameras.
Had two repairs with my mechanical cameras.
If an electronic film camera is well designed, like the professional Nikon and Canon film cameras for example, it will serve you for decades.
And by the way: What is the "heart" of a camera? It is the shutter.
And the shutters of the EOS 1 V, F5, F6, Dynax 9 etc. are designed for robustness and durability in professional use, with a minimum of 150,000 - 200,000 releases.
The local Nikon professional service some years ago had a F5 from a customer (working flawlessly) with a number of shutter releases of 1 million (!!) releases.
You will not get that from a Nikon FM(2), Pentax MX, Minolta SRT, Olympus OM-1/2 etc.
Their shutters are not designed for that heavy use.
The main question for long term durability is not whether you have a purely mechanical camera or a film camera with electronic parts.
The main question is: How well is the camera designed and built.
And my Nikon F6 is definitely more robustly and better built than my former old F2 or younger FM2.