What Admiral Nakhimov's refit reveals

What does Admiral Nakhimov's long refit and the retirement of other Kirov-class ships indicate?

Modernizing such a complex old cruiser is extraordinarily prolonged and costly, limiting the practical value of nominal hull numbers.

The ship's prolonged refit reflects the challenge of replacing obsolete systems and rebuilding a large nuclear-powered combatant around new weapons and electronics. Its duration also complicates claims that retaining an old hull automatically creates usable fleet strength.