You can't simply swap out the guidance and control systems of state of the art kit for a bunch of chips 5 years older. That's not how high performance embedded systems engineering works. Older chips need more power so bigger batteries, produce more heat, take up more space, have lower performance, all inside a missile, munition, satellite or fighter jet with extremely limited space and exacting design tolerances.
The best you could do is go back to making older systems for which the factories may not exist anymore, or design and build new systems using the old CPU tech and new everything else. Both options would impose a severe economic and military cost and take years to implement.
It doesn't matter that 5nm chips aren't used in military hardware today. You can bet military hardware is being designed now that will use 5nm chips. Therefore access to that production capacity is strategic.
The best you could do is go back to making older systems for which the factories may not exist anymore, or design and build new systems using the old CPU tech and new everything else. Both options would impose a severe economic and military cost and take years to implement.
It doesn't matter that 5nm chips aren't used in military hardware today. You can bet military hardware is being designed now that will use 5nm chips. Therefore access to that production capacity is strategic.