They’re already in place that has enough drag. The satellites will deorbit in months to years without periodic boosts. Debris will come down faster, since they

They’re already in place that has enough drag. The satellites will deorbit in months to years without periodic boosts. Debris will come down faster, since they have more surface area relative to their mass. A single impulse always results in an orbit that intersects the original orbit at the location of the impulse, so it’s impossible for a collision to raise debris entirely beyond that altitude.