Orbits themselves don't move, they're time-invariant (short term, but so is the ground). Six numbers are all it takes to define an orbit; if you put something on it, it stays there and blocks it off - like building on a plot of land.
Anyway, Starlink wants to scale up to 42,000 satellites. I can't imagine that's anywhere close to the maximum number that could fit in their altitude range. After all, if arranged in a grid, that's just ~ 200 x 200 satellites. The earth's surface area is many orders of magnitude larger than that, and the satellites are occupying a larger (and much thicker) orbital shell.