Materials aging in space is a pretty deep subject. That it is the Russian Zvevda module that is leaking/cracking is likely related to the fact that it is also the oldest module in the ISS. The ISS is/was scheduled to be retired in 2024 (aka 3 years from now) but there are calls to keep it going. My fantasy would be to have SpaceX move it into the Lunar L1 Lagrange point which would keep it in use but it would have to…
Is there any reason to park in at a Lagrange point instead of just a high orbit? There aren't that many Lagrange points, so we should probably avoid cluttering them with objects that don't need to be there.
Geosynchronous orbits are above the worst parts of the radiation belts, so maybe that's a good place for the ISS. Or even higher; it doesn't need to be geosynchronous. The main advantage of a low orbit is that it's easier to get to from Earth, but if you're just parking it long-term as a museum piece that doesn't matter as much.
I wouldn't expect Lagrange points to have much of a problem with clutter unless we decide to start parking enormous quantities of stuff there. Objects can spread out and orbit the points; as long as they're all going in about the same direction they should be able to avoid running into each other.