[InclinedPlane]

This is simply ignorant of the plans. Firstly, there are levels of functionality, being able to provide service being the highest one. Out of service satellites are still most likely to be able to execute a controlled re-entry. Secondly, these satellites will be in low Earth orbit. If they become completely inoperable they have an orbital lifetime of only a few years before they re-enter. Only with routine station keeping maneuvers can they stay in orbit for even their sub-decade planned lifetimes. So there's very little risk of a Kessler syndrome type situation developing. At any given time the number of derelict satellites in orbit would be quite small if not zero.

[kobeya]

> Out of service satellites are still most likely to be able to execute a controlled re-entry

How? By a burn? That's a lot of fuel reserve to use up.

[Retric]

It takes minimal energy to deorbit from LEO. By changing the shape of the orbit you spend some time in denser atmosphere which increases drag which quickly deorbits you. Controlled just means they start the processes at a specific time.

[InclinedPlane]

How much reserve fuel does an out of service satellite need to use after it burns up in Earth's atmosphere?

How much fuel do you imagine it takes a satellite to re-enter if it will happen automatically in a matter of a few years?

The answer to both is, of course, not much, not much at all.