Re: ISS' swansong?
Is there any reason that what you propose could NOT simply extend the existing ISS? One "connection module" at a docking port and you end up with "the old station" attached to the new, a kind of "city planning" if you think about it.
That's kind of what they're planning with some of their commercial partners. Some new-space companies are looking at launching modules to the ISS which can borrow station power/utilities but develop revenue immediately as a science lab or whatnot. Then over time they'll launch additional utility modules on with the intent of undocking whenever ISS finally goes EOL and become their own independent station (or redock with other private modules). Axiom Space is the main name at the moment.
Not quite the same as ships forming a raft around a common hub, but one of the ways NASA is helping lower the bar to entry for private operators.
Sooner or later though, the core ISS will develop enough leaks and have enough stuff breaking that it'll be cheaper to deorbit and replace than keep going.