Spaceflight

They have already done this study, though.

https://www.nasa.gov/wp-content/uploads/2024/06/iss-deorbit-analysis-summary.pdf?emrc=667c97a20241b

Raising to even a 100 year safe orbit needs 20,000kg of propellant and a new vehicle that doesn't exist. I suppose that's solvable with enough budget. It would also need attitude control while raising the orbit for debris avoidance. And a crew. Getting crew to dock at 650km is prohibitive for a mix of reasons. And, even if you solve those issues, the station becomes a dead bomb in the parking orbit that could create a massive debris cloud if struck.