Most modern MOS circuits are no longer designed to last 50 years, unlike most integrated circuits and discrete semiconductor devices of 50 years ago. There is no chance for any up-to-date CPU or memory module to work for 50 years.
Nevertheless, it is quite easy to be able to use a modern computer for 50 years, if you just get 10 computers that do not contain components that age even when they are not used, e.g. batteries or electrolytic capacitors, and you use one computer until it breaks, keeping the others in storage until you must replace the current work computer.
Such a set of modern computers would be faster, cheaper and smaller than a single computer in the style of PDP-11 or VAX, made by using low-density components that can work for 50 years.
Nevertheless, it is quite easy to be able to use a modern computer for 50 years, if you just get 10 computers that do not contain components that age even when they are not used, e.g. batteries or electrolytic capacitors, and you use one computer until it breaks, keeping the others in storage until you must replace the current work computer.
Such a set of modern computers would be faster, cheaper and smaller than a single computer in the style of PDP-11 or VAX, made by using low-density components that can work for 50 years.