Japan is known for innovative technology as much as Europe is.  I think you're just being racist towards Asians.

China will continue to be the world leader in mining and some other reasonably stable businesses which can be ran with Bitcoin.  However, this is not inherently a problem to decentralisation - the problem only occurs when this business is concentrated in the hands of just a few people.  Unfortunately, mining is concentrated in the hands of a few people, but this is nothing to do with "China" per se, as if it is one single entity.

So in that sense, no one will be a world leader because the only people that have control are the miners (which can be anyone and Chinese monopolies can be dethroned at any point by businesses) and the developers (as well as those holding Bitcoin).