After a big event like that there would most likely be significant climate forcing (likely toward cold, perhaps toward hot). Plus, there wouldn't be much overall damage to the landforms because most of the modern weaponry is designed to kill people rather than equipment. But as they've stated, 1000 years is a long time. Look at what happened to Rome, for example, from 400 to 1400 (everything fsilted up and forests grew on them).

So 1000 years after a good whack you'd likely have a world in an ice age with mounds of rust and debris covered in vegatation ecept in desert regions. The hardest hit areas would be in the northern hemisphere with the southern hemisphere likely less damaged. I would recommend finding a good ice age map and laying a modern road grid over it. You can make your own from some of the better bathymetric sets out there such as ETOPO2.