Writing this answer to When will the ISS deorbit? I came across Space Policy Online's NASA Solidifies Planning to Deorbit ISS in 2031 and the image below.
It shows the estimated last crew occupying the ISS from roughly May through October 2030.
During that period the ISS' altitude prediction drops from 320 to 280 km, and appears to drop to zero only one month after that.
Question: Why 280 km? Why so late? Isn't staying until one month before reentry cutting things kinda close?
I guess there might be an extra escape craft docked as a contingency and/or something on the ground ready to launch, but still...
From NASA Solidifies Planning to Deorbit ISS in 2031:
ISS average altitude estimates targeting re-entry early 2021
Figure 4. shows the ISS end-of-life de-orbit altitude, cargo resupply, and de-orbit plan assumptions. This timeline assumption is reflected in the budget discussion above for de-orbit vehicle procurement.
