It would come down, most of it very quickly, the rest eventually. The satellites are low enough to deorbit from drag alone within five years or so if their thru

It would come down, most of it very quickly, the rest eventually. The satellites are low enough to deorbit from drag alone within five years or so if their thrusters fail. Blowing them up increases surface area, which increases drag, bringing most of it down much faster. The way orbit mechanics works, if you impart energy on an object at just one point in its orbit, the orbit will change overall but still go through that point. Some debris will be put in an elliptical orbit where it will start crossing higher altitudes, but will also still cross the original altitude, causing it to be affected by drag and eventually deorbit. The worry is what it would damage until it comes down. At some debris density you start setting off a chain reaction (and arguably we are already there, it's just very slow right now)