A CMS can be the right tool for years and still become the wrong tool later. The warning signs are usually familiar: updates feel risky, forms are unreliable, hosting is confusing, and simple edits require too much effort.
Replacement makes sense when the public site is mostly stable content but the platform still carries database, plugin, security, and server maintenance overhead.
The best migration preserves what has business value, retires what does not, and leaves the team with a site that is easier to understand after launch.