Do you mean a threat to China's status as leading economic power, or a threat to China? Improvements in productivity help all of us, because we make more stuff to share around; it is not a zero sum game.
I believe if they are successful they will be a threat to China's economic growth and their border disputes may spill out into more explicit hostilities.
From an economic standpoint they may be able to put together cost competitive manufacturing facilities with a better quality of life for their workers. That, coupled with the increasingly forceful way in which China struggles to maintain its margins are threatening the delicate balance in China between the benefit of hard currency and the challenge of an upwardly mobile workforce. (or not which would turn out to be the problem)
As more companies are put under pressure to avoid doing business with companies like FoxConn and the ability to keep information about working conditions in China out of the press is reduced. It makes for a challenging environment for the Chinese. To have a neighbor state pick up the slack with workers who, if they are successful can move on to big houses and a more affluent lifestyle, and are thus both happier and more productive in their jobs. That is the threat economically.
If India were to provide a ready market for Afghanistan's raw mineral wealth, that too could be problematic for the Chinese.
Aren't they they same. We are all on one big rock and access to petroleum, water, and food will become more limited and more contested as both economies grow. Economically and realistically, India is a threat to China, Europe and the US.
