Around here, firemen just yank the meter. Easy peasy.
That's what they do here, too, for structures that are not yet up to current code, like my place.
However, our city and county update their codes to match current NEC, and an external means of disconnect is now required.
To do any of the work we're discussing here requires a building permit and several electrical inspections for the project. If you do it yourself, you could sneak the work and avoid all of that. Just not legally.
But if you hire an electrician to do the work, they must pull the permit and have the inspections unless they don't mind risking their license. So for most people, a project like this here will end up requiring all of these issues being brought up to current NEC. As long as you don't do any work, these existing systems are grandfathered, at least until you try to sell the property.
Also, the local electrical inspector is now my wife's ex. So I'm pretty sure we would get a rather thorough inspection!
Actually, he and I get along fine, much to my wife's dismay.