Unofficial reports are saying the drone was equipped with self-destruct mechanisms to destroy senitive material.
Even if China or
Russia are able to reverse engineer this drone technology, they're years behind the USA in military technology. The version of drone that the US lost has been in use for 3 years. Its lifespan was coming to an end and new technology is down the pipeline.
Nobody
EVER imagined a stealth helicopter existed until recently. A former defense contractor said to imagine the craziest military technology you can imagine in your mind, and the US has already developed it in real life.
The US Military Industrial Complex is so far ahead of the rest of the world it's staggering. It's comperable to
horse drawn buggy Vs. automobile.

Recently
Russia has threatened to target missle defense sites the US plans to build in Europe.
The US response was 
The USA is the world's boss. To dispute that is denial of the truth.