They might not be able to fully utilize some of the really high-tech stuff left behind - but the Chinese, Russians, and North Koreans will be more than happy to take it off their hands for a reasonable price so they can study it and reverse-engineer it.
The other stuff tho', particularly the road vehicles, tanks, and small arms - yeah, they'll get the hang of that stuff, and it will make them much more dangerous than they are right now.